Investigators gather at the scene after an explosion caused by a suspected suicide attack killed four people, including three Chinese teachers. The bombing happened at the entrance of the Confucius Institute at Pakistan’s University of Karachi on Tuesday. Photo: Akhtar Soomro/The Paper

Security personnel guard the site of the attack on Tuesday. The blast damaged the minibus that carried the victims. Photo: Rizwan Tabassum/VCG

Investigators survey the damaged minibus. A Pakistani separatist group, the Balochistan Liberation Army, has claimed responsibility for the attack, saying the attacker was a mother of two. Photo: Fareed Khan/VCG

The charred remains of the interior of the minibus. Photo: Fareed Khan/VCG

Investigators mark out evidence found at the site of the attack. Photo: Fareed Khan/VCG

A damaged motorcycle at the site of the attack on Tuesday. Photo: Shahzaib Akber/The Paper

Security staff patrol the entrance of the Confucius Institute. The University of Karachi and China’s Sichuan Normal University jointly established the institute in 2013. Photo: The Paper

Investigators and journalists gather at the scene following the explosion. Photo: Fareed Khan/VCG

Ambulances wait in line to get the wounded to hospital. Among the injured was a Chinese teacher. Both Chinese and Pakistani officials condemned the attack and expressed condolences for the victims and their families. Photo: Sabir Mazhar/VCG