From correspondents in Islamabad, Pakistan, 01:30 PM IST

A powerful blast shook the police headquarters here Wednesday, officials said. It was not immediately known if there were any casualties.

The explosion was heard more than 10 km away. 'It seems to be a suicide attack,' said a police officer.

Residents of the neighbourhood said that smoke could be seen coming out of the police headquarters that is located near two main universities and three hospitals.

Although it was not immediately clear if anyone was injured or killed, TV channels quoted officials as saying heavy casualties were feared.

The blast occurred even as a joint session of the parliament was being briefed by senior military officials on the measures taken to counter terrorism.

(Staff Writer, © IANS)