At least 4 killed in Islamabad blast-reports

ISLAMABAD, July 17 (Reuters) A blast was heard in the Pakistani capital Islamabad today, Reuters witnesses reported, and a television station said at least 4 people were killed.

It was not immediately clear what caused the blast.

Pakistan has seen a surge in violence since government forces stormed Islamabad's Lal Masjid, or Red Mosque, compound earlier this month ending a week-long siege and killing supporters of a hardline cleric.

Reuters LPB DB2132