Question: Dale Cregan was sentenced to life imprisonment for the murder of two police officers. The officers were responding to a report of a what?

Context articles: Murders of Nicola Hughes and Fiona Bone
Life imprisonment in the Netherlands
2009 shootings of Oakland police officers
Frank Jude, Jr.
Dale Cregan
Kuwasi Balagoon
Police Truck
2009 shooting of Pittsburgh police officers
Kite Liberator
May 2009 Dera Ismail Khan bombings

On 18 September 2012, Police Constables Nicola Hughes and Fiona Bone, two Greater Manchester Police officers, were killed by Dale Cregan in a gun and grenade ambush while responding to a report of a burglary in Greater Manchester, England.
Since the abolition of the death penalty in the Netherlands in 1870, life imprisonment has almost always meant imprisonment until death; unlike in other countries in Europe, there is no possibility of parole for anyone sentenced to life imprisonment.
 Though the prisoner can appeal for pardon, it must be granted by royal decree; since the 1970s, only two such pardons have been successful, both being terminally ill.
 Since 1945, 41 criminals (excluding war criminals) have been sentenced to life imprisonment.
 There has been a noticeable increase of life imprisonment sentences being given in the last decade, and more than triple the number of life imprisonment sentences in the last few years than the previous decades.
On March 21, 2009, Lovelle Mixon, a convicted felon wanted on a no-bail warrant for a parole violation, fatally shot four Oakland, California police officers.
 Mixon initially shot and killed two Oakland police officers during a traffic stop.
 After escaping on foot to the nearby apartment of his sister, Mixon then killed two police SWAT team officers attempting to apprehend him.
 Mixon was then killed as officers returned fire.
Frank Jude, Jr., a.k.a. Frankie Lee Jude, Jr., (born August 14, 1978) is a Wisconsin man who was severely beaten by off-duty Milwaukee police officers in the early-morning hours of October 24, 2004.
 Following a state trial that ended with the jury acquitting the three police officers charged, a federal investigation led to plea agreements with three police officers and the indictment of five police officers, including the three who were acquitted in state court.
 Before trial, one of these five pleaded guilty.
 The federal jury acquitted one of the remaining police officers and the three police officers who were acquitted in state court were convicted in federal court.
Dale Christopher Cregan (born 6 June 1983) is an English convicted drug-dealer and murderer who was sentenced to a whole life order in prison for four counts of murder (including the killing of two police officers) and three separate counts of attempted murder, meaning that he will never be released from prison.
Kuwasi Balagoon (December 22, 1946 – December 13, 1986), born Donald Weems, was a Black Panther, a member of the Black Liberation Army, a New Afrikan anarchist, and a defendant in the Panther 21 case in the late 1960s.
 Captured and convicted of various crimes, he spent most of the 1970s in prison.
 Balagoon escaped from prison several times, going underground and resuming BLA activity.
 He was finally captured and charged with participating in an armored truck armed robbery, known as the Brinks robbery (1981), in West Nyack, New York, on October 20, 1981, an action in which two police officers, Waverly Brown and Edward O'Grady, and a money courier (Peter Paige) were killed.
 Convicted of murder and other charges and sentenced to life imprisonment, he died in prison of pneumocystis pneumonia, an AIDS-related illness, on December 13, 1986, aged 39.
 Balagoon was bisexual.
"Police Truck" is a song by the Dead Kennedys.
 The song was originally released in May, 1980, as the B-side of the "Holiday in Cambodia" single and later released in June 1987 on the DKs' compilation album, "Give Me Convenience or Give Me Death".
 The song is a satirical attack on the actions of two police officers, and takes a first person view from the authorities themselves.
 The song was inspired by an incident that occurred in Los Angeles in the late 1970s in which two police officers performed illegal activities such as drinking on the job, beating up drunks, and raping prostitutes.
 It also functions more generally as an attack on police corruption and brutality and the police's support for a capitalist system.
On April 4, 2009, a shootout occurred at 1016 Fairfield Street in the Stanton Heights neighborhood of Pittsburgh, Pennsylvania, United States, stemming from a mother and her 22-year-old son's argument over a dog urinating in the house.
 At approximately 7:11 a.m. EDT, 22-year-old Richard Poplawski opened fire on two Pittsburgh Police officers responding to a 9-1-1 call from Poplawski's mother, who was attempting to get the police officers to remove her son from the home.
 Despite Poplawski's mother telling the 9-1-1 operator that Poplawski had guns, the police officers were not told.
 Three police officers were ultimately confirmed dead, and another two were seriously injured.
Taking place ten years after the events of the original "Kite" film, this second installment opens with Kōichi Doi, a researcher for Defy Foods, boarding the International Space Station.
 Doi had been researching methods of preserving bone mass in zero gravity through diet.
 After Orudo Noguchi and another crew member are later found to have space radiation exposure and ordered to discontinue missions, Noguchi asks Doi to deliver a package to his daughter Monaka for her birthday.
 Meanwhile, in Tokyo, two police officers pursue a violent criminal named Tsuin through the streets and into a train station.
 After shooting two bystanders in the women's restroom, he takes a young girl hostage and hides in a stall with her.
 However, the lights go out in the restroom and he is attacked by the assassin known as Sawa the Angel of Death who quickly disarms and shoots him, leaving a pile of feathers on his corpse.
 Later that night, Monaka, the girl that currently assumes the identity of Sawa, goes to work at Apollo 11, a maid cafe with a perverted regular patron.
 Monaka plays the part of a nerdy, clumsy high school girl while in public making her a vulnerable target for harassment.
 Monaka's older co-worker Manatsu Mukai does not take kindly to that, however, and retaliates in several occasions, such as spiking his drink with habanero or kicking him in the crotch.
 Monaka's manager later receives a phone call from the real Tsuin, who names Rin Gaga (one of the two police officers who pursued the pedophile that night) as the other Tsuin's killer.
On May 14, 2009, three Hand Grenades were thrown on Police officers in Dera Ismail Khan.
 A motorcycle rider threw a hand grenade on police emergency office.
 According to local Police Chief of city, Muhammad Iqbal, 5 police officers were wounded in first grenade's explosion three of whom were seriously hurt.
 In the next half an hour, two more grenades were lobbed on two police posts near a bus stand.
 Four police officers were injured in next two explosions.
 In all the three explosions, 9 police offers were injured.
 All injures were brought to a state–run hospital.
 Ashiq Saleem, doctor at hospital, said, "we have received eight injures, three of them are serious, all of them are police officers."
 No group have yet claimed responsibility for attacks.