Gunmen kill 43 in bus attack in Pakistan's Karachi

People gather as rescue workers and volunteers makes way for ambulances, carrying bodies of the victims of an attack on a bus, as they move outside the hospital in Karachi, Pakistan, May 13, 2015. REUTERS/Akhtar Soomro

KARACHI, Pakistan (Reuters) - Gunmen on motorcycles boarded a bus and opened fire on commuters in Pakistan's volatile southern city of Karachi on Wednesday, killing at least 43, police said, and militants affiliated with Islamic State claimed responsibility.

The pink bus was pockmarked with bullet holes and blood saturated the seats and dripped out of the doors on to the concrete.