MIR ALI, Pakistan—An American missile killed two Arab militants and two local fighters as they traveled in a vehicle close to the Afghan border on Monday, the fourth such attack in the space of 24 hours in the region, Pakistani intelligence officials said.

The vehicle was laden with explosives when it was struck in the village of Malik Jashdar in North Waziristan, said the officials.

The identities of the men were not released.

Since 2008, the United States has fired hundreds of missiles from unmanned planes at al-Qaida and Taliban targets, killing scores of militants. It does not acknowledge the program or give details on who it is killing. Pakistan formally protests the strikes because they are unpopular among many in the country, but gives intelligence for at least some of them.

Four strikes in the space of 24 hours represents an intense barrage, but is not unprecedented. Sunday’s attacks killed seven militants, officials said. Two strikes were in North Waziristan, while the third was in South Waziristan.

North Waziristan is home to local and foreign militants battling the Pakistan state as well as those fighting foreign and Afghan troops across the border in Afghanistan. The Pakistani state has very little presence in North Wazristan. Reporters who have visited say it is under effective control of the insurgents.