At least 13 people were killed and 47 wounded when a bomb exploded in a market on Saturday in a mainly Shiite area of Pakistan's northwestern tribal belt, officials said.
The blast happened in a crowded vegetable market in Parachinar city, the capital of Kurram tribal district on the Afghan border where officials said the death toll was expected to rise.
"At least 13 people have been killed and 47 wounded," Ikramullah Khan, a senior government official in Parachinar, told AFP.
Khan said the blast was caused by an IED (improvised explosive device) which was hidden in a vegetable box.
Noorullah Khan, an official in Parachinar hospital, told AFP that 11 bodies and more than 40 injured had been taken to the hospital.
Pakistan military said soldiers had reached the site and cordoned off the area.
"Army helicopters are evacuating the injured," it said in a short statement.
Kurram is one of Pakistan's seven semi-autonomous tribal districts which are governed according to local laws and customs.
The district is known for sectarian clashes between Sunnis and Shiites, who make up roughly 20 percent of Pakistan's population of 200 million.