NAIROBI, Kenya — A U.S. drone strike in Somalia on Thursday is believed to have killed a senior member of the al-Shabab extremist group who allegedly helped plan the 2013 Westgate Mall attack in Nairobi, officials said.

Adan Garar and two others are suspected to have been killed after their car was targeted near the town of Bardhere, the Kenyan and U.S. officials said.

The senior Kenyan official, who insisted on anonymity because he wasn't authorized to give the information to the media, says Garar is also suspected of planning failed attacks on Kenya's coast and in the Ugandan capital, Kampala, last year. The U.S official also insisted on anonymity.

Anti-terror police foiled a planned attack in the coastal city of Mombasa after they intercepted a car packed with explosives in March 2014, according to Kenyan authorities. According to police, al-Shabab militants had planned simultaneous attacks on the international airport in Mombasa, the ferry crossing and a supermarket. The car laden with explosives was to be detonated on a ferry.

Al-Shabab, an Islamic extremist group, has vowed to inflict violent attacks on Kenya and Uganda because the two countries have contributed troops to the African Union force supporting the government in Somalia.

Sixty-seven people were killed in the Westgate attack, which was carried out by four gunmen from al-Shabab.

___

Associated Press Writer Lolita C. Baldor contributed to this report from Washington.