At least three al-Qaida suspects were killed and four others injured in a U.S. drone strike in Yemen's southern province of Abyan on Tuesday night, local officials said.

The strike occurred at about 1:00 p.m. local time (1000 GMT) when a U.S. drone targeted an al-Qaida-held site in Abyan's town of Mahfad. The drone fired three missiles and destroyed two huts and a site used as a training center for al-Qaida militants in a mountainous region in Mahfad town.

Local residents said that the death toll may further rise, as the injured were in critical condition. Two drones are still hovering over the area.

Identities of the killed and injured are not known yet.

The United States has escalated its drone strikes on suspected al-Qaida targets in Yemen since February 2012, when Yemeni President Abd-Rabbu Mansour Hadi took office after a UN-backed deal removed former President Ali Abdullah Saleh from power.

Last month the White House pledged to continue to support the counter-terrorism efforts of Hadi's government, aiming to uproot al-Qaida group in Yemen.

But critics say that the drone strikes often violate international law and cause heavy civilian casualties. In December 2013, a U.S. drone strike mistakenly hit a wedding party in Yemen' s southeastern province of al-Bayda, killing 11 civilians and wounding 21. Endi