Islamabad, Pakistan (CNN) -- The death toll from a trio of suicide attacks during a Shiite processions in Lahore, Pakistan, grew to 31 on Thursday, authorities said.
Khalid Ranjha, a Lahore government official, said Thursday that 340 people were injured in Wednesday's blasts, which left seven people critically wounded.
The three explosions occurred within a radius of about 600 meters (2,000 feet). The Pakistani Taliban, also known as Tehrik-e-Taliban Pakistan or TTP, claimed responsibility Thursday for the attacks, a TTP spokesman told CNN.
All three blasts were the work of suicide bombers, said Nayab Haider, a spokesman for the Lahore police. Police tried to stop the first suicide bomber as the procession was ending, but he blew himself up as a police officer caught up with him in the crowd, Haider said.
Three or four minutes later, the second blast erupted. It was followed 25 minutes later by a third suicide bomber. Police have found two heads and one body separately, said Haider, who said authorities had assigned 2,500 police officers to the procession after receiving a warning that it might be attacked.
Khusro Pervez, a senior government official, said the incidents took place around the time of the daily breaking of the Ramadan fast, and security may have been lax.
"At the end of the procession, security should have been more vigilant," Pervez said. "The incident happened because of security breach."
Pakistan is a largely Sunni Muslim nation, and the attack on Shiite Muslims conjures thoughts of the long-standing tensions between the two groups in the Middle East and Asia.
Paramilitary forces have been deployed to the streets to bring order. Local TV channels showed pictures of angry people burning vehicles, beating police and trying to break into a police station.
CNN's Samson Desta contributed to this story.