Question: How many bombs were used in the attack that killed Tim and Jonathan Ball?

Context paragraphs:
Media24 Books Literary Awards: The Media24 Books Literary Awards (Known pre-2011 as the Via Afrika Awards) are a group of South African literary prizes awarded annually by Media24, the print-media arm of the South African media company Naspers.  They are open to authors whose books are published within the Media24 Books stable, which includes NB Publishers, Jonathan Ball Publishers, LuxVerbi-BM, NVA, and Van Schaik Publishers.  The awards were worth R35 000 each in 2013.

Talmenes chemical attack: The Talmenes chemical attack took place on 21 April 2014, in the village of Talmenes in Idlib Governorate of Syria.  The village was struck by a chemical attack around 10:30 when two “barrel bombs” embedded with cylinders of chlorine gas reportedly were dropped on the village.  The bombs struck two houses some 100 m from each other, in the neighbourhood around the “big” mosque. <ref name="S/1230/2014"> </ref> According to Human Rights Watch, the attack killed three civilians and wounded about 133.

Volcanic bomb: A volcanic bomb is a mass of molten rock (tephra) larger than 64 mm (2.5 inches) in diameter, formed when a volcano ejects viscous fragments of lava during an eruption.  They cool into solid fragments before they reach the ground.  Because volcanic bombs cool after they leave the volcano, they are extrusive igneous rocks.  Volcanic bombs can be thrown many kilometres from an erupting vent, and often acquire aerodynamic shapes during their flight.  Bombs can be extremely large; the 1935 eruption of Mount Asama in Japan expelled bombs measuring 5–6 m in diameter up to 600 m from the vent.  Volcanic bombs are a significant volcanic hazard, and can cause severe injuries and death to people in an eruption zone.  One such incident occurred at Galeras volcano in Colombia in 1993; six people near the summit were killed and several seriously injured by lava bombs when the volcano erupted unexpectedly.

Riaan Manser: Riaan Manser (born 1973) is a "pioneering explorer", based in South Africa.  He was the first person to circumnavigate the coast of Africa by bicycle, a distance of 37,000 km, through 34 countries over two years and two months.  In July 2009 he became the first person to kayak 5,000 km around Madagascar, alone and unaided.  Both journeys are covered in his books, "Around Africa on My Bicycle" (Jonathan Ball Publishers, 2007) and "Around Madagascar on my Kayak" (Jonathan Ball Publishers, 2011).  In 2011 he also circumnavigated Iceland in a two-man kayak with Dan Skinstad.  .  His most recent journey, "Take Me 2 New York" started in December 2013 with his long-time girlfriend, Vasti Geldenhuys.  They rowed from Morocco, Africa to New York City, USA in an ocean rowing boat alone and unaided.

The Bomb (film): The Bomb is a 2015 American documentary film about the history of nuclear weapons, from theoretical scientific considerations at the very beginning, to their first use on August 6, 1945, to their global political implications in the present-day.  The two-hour PBS film was written and directed by Rushmore DeNooyer, who noted the project took a year and a half to complete, since much of the film footage and images was only recently declassified by the United States Department of Defense.  According to DeNooyer, “It wouldn’t take very many bombs to really change life on Earth, ... The idea that there are thousands of them sitting around is pretty scary.  I don’t think people today realize that.  They don’t think about it.  I don’t think they are scared.  But in a way, they should be.”  Mark Dawidziak, of the "Cleveland Plain Dealer", summarized the film as follows: ""The Bomb" moves swiftly to cover Hiroshima and Nagasaki, the Cold War, the arms race, the Red Scare, the witch hunt, the Cuban Missile Crisis, test-ban treaties, the "Star Wars" initiative, the anti-nuke movement, the collapse of the Soviet Union and the rise of new nuclear threats."  According to historian Richard Rhodes, “The invention [of 'The Bomb'] was a millennial change in human history: for the first time, we were now capable of our own destruction, as a species.”

Warrington bomb attacks: The Warrington bombings were two separate bomb attacks that took place during early 1993 in Warrington, England.  The first attack happened on 26 February, when a bomb exploded at a gas storage facility.  It caused extensive damage but no injuries.  While fleeing the scene, the bombers shot and injured a police officer and two of them were then caught after a high-speed car chase.  The second attack happened on 20 March, when two small bombs exploded in litter bins outside shops and businesses on Bridge Street.  Two children were killed and dozens of people were injured.

March 9, 2004 attack on Istanbul restaurant: On March 9, 2004, an attack on a restaurant in the Kartal district of Istanbul, Turkey killed Hüseyin Kurugöl, a waiter in the restaurant, and injured five others.  The two Islamic militants who carried out the attack, Engin Vural and Nihat Doğruel, were holding automatic weapons and had ten homemade pipe bombs strapped to their flak jackets when they entered the restaurant frequented by freemasons.  Shooting the guard in his feet, they entered the dining hall and began firing at the forty people in the room.  Then they detonated bombs at the entrance, killing Kurugöl.  One of the militants died in the attack, the other was seriously injured.

Jonathan Ball (soccer): Jonathan Ball (born January 6, 1986) is a Bermudian football player, who currently plays for PHC Zebras.

The Tim Parry Johnathan Ball Foundation for Peace: The Tim Parry Johnathan Ball Foundation for Peace is an educational peace charity based in United Kingdom (charity no.1048990).  It was formed in 1995 by Colin and Wendy Parry, following the loss of their 12-year-old son Tim and 3-year-old Johnathan Ball in the 1993 Warrington bomb attacks, which were perpetrated by the Provisional Irish Republican Army.

Jonathan Ball (architect): Jonathan Ball MBE (born 1947) is the co-founder of the Eden Project in Cornwall, UK.  He sits on the RIBA National Council

Supporting paragraphs: The Tim Parry Johnathan Ball Foundation for Peace Warrington bomb attacks
Answer: two small bombs