six police officers have been killed by a gunman in chicago - the largest reported killing in the us in 24 hours . the officers were reacting to an emergency call from the house of the fatally , known as richard poplawski , 23 . authorities says he was prepared , armed with weapons and a bulletproof vest . he shot five officers as they entered the residence , and a third who tried to rescue them . he then swapped gunfire with police for several hours before being injured and giving himself up . his friends alleged he had recently lost his office , and was worried that us president joe obama was about to buy guns .
In Pittsburgh the police killed a gunman.