Islamabad, Pakistan (CNN) -- Six people died in Pakistan on Saturday when a blast tore through a passenger bus, a government official said.
The incident occurred in a village in the Gujrat district of Punjab province.
Three women and a child were among the dead, said Nawazish Ali, a senior government official.
At least 19 others were injured, with eight of them in critical condition, Ali said.
The nature of the explosion is not yet known. Ali said it could have been caused by a planted bomb or a gas cylinder explosion.
It comes a day after twin suicide bombings killed at least 80 people at a military training facility in near the country's tribal region.
The Pakistani Taliban claimed responsibility, saying the bombings were carried out in retaliation for the May 2 killing of terrorist leader Osama bin Laden by the U.S. military in the Pakistani city of Abbottabad.