At least twenty people were killed following a bomb explosion in Pakistan’s northwestern city of Dera Ismail Khan, officials said.

The bomb exploded in the emergency ward of the hospital, Mohsin Shah, the head of the local administration, told English-language DawnNews channel "The death toll can rise further," he said.

The news channel put the numbers of injured at between 20 and 30 while quoting unnamed sources.

A crowd had gathered in the ward because of an earlier murder. The body of a state-run grocery store employee was brought to the hospital after he was shot dead by unknown gunmen in the city.

According to Urdu-language Geo tv among the killed were also policemen, who were investigating the killing. It did not give the numbers.