CAIRO - At least 11 Egyptian policemen were killed on Tuesday in an explosion hitting police armor in the North Sinai's Rafah city, a security official told Xinhua.

The blast happened as the vehicle was passing on a planted explosive device in Wefaq village, the same village where eight extremists were killed in a military raid on Sunday including head of the Sinai-based Ansar Bayt al-Maqdis group, added the official.

Other four security personnel were seriously wounded in the attack.

Following the blast, unknown militants exchanged fire with the police forces, and a status of high alert was declared, official news agency MENA reported, adding the death toll may increase due to bursting strength of the blast.

In July, over 50 extremists were killed in military raids in response to the killing of police and military officers by gunmen.

Militant attacks, which usually target security personnel, but also led to civilian casualties, have surged since the ouster of Islamist president Mohamed Morsi in July 2013 and the harsh crackdown on his supporters.

Sinai-based al-Qaida-inspired Ansar Bayt al-Maqdis group claimed responsibility for most of the attacks against the security personnel.

The military has poured armor and soldiers into Sinai to root out the militants who have killed more than 500 security personnel across the country since August 2013.

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