Airstrikes killed at least 50 people in northwestern Pakistan on Wednesday as the military pressed a month-old offensive to rid the region of violent extremists, officials said.

One strike targeted a house in North Waziristan as well as a vehicle passing nearby, local intelligence officials said. Although authorities said 15 people were killed in the strike, some officials said at least 20 died.

Several local officials said they thought the strike was carried out by a U.S. drone. However, the CIA declined to comment.

“The compound was being used by foreign militants, and some local terrorists were present in the vehicle that got targeted,” said one of the Pakistani intelligence officials, who spoke on the condition of anonymity because he was not authorized to talk to the media.

The attack occurred in an area suspected of housing fighters affiliated with the Afghan Haqqani network as well as Islamist militants from Uzbekistan, local officials said. One villager said he saw the aircraft fire at least four missiles.

Also Wednesday, a separate Pakistani airstrike killed 35 suspected terrorists who were trying to flee North Waziristan, military officials said. Since the start of the military operation, at least 450 militants have been killed in the region, they added.

There have been at least two U.S. drone strikes in Pakistan since the military offensive began. It is designed to drive Pakistani Taliban and other militants from North Waziristan, which extremist groups have been using as a base to carry out attacks in Pakistan and nearby Afghanistan.

Most senior militant leaders are thought to have escaped before the operation began. But Pakistani military commanders say their offensive will permanently disrupt the ability of terrorist groups to congregate in the country’s restive tribal areas.

Both U.S. and Pakistani officials have denied that the two countries are coordinating military activities in North Waziristan.

After a suspected U.S. drone strike killed several people last week, Pakistan’s Foreign Ministry condemned it, saying in a statement that the attack would have “a negative impact on the Government’s efforts to bring peace and stability” to the country.

But Prime Minister Nawaz Sharif and other leaders have generally appeared more tolerant of the CIA drone campaign since the North Waziristan operation began.

Although the number of drone attacks in Pakistan continues to decline, President Obama has said such strikes will keep targeting those who threaten U.S. troops or interests in Afghanistan.

It is difficult for foreign journalists to independently verify Pakistani military claims because they are generally not permitted to travel to tribal areas. For weeks, Pakistan’s military has also refused to identify those killed in the operation.

But Tuesday, Pakistani intelligence officials said senior Pakistani Taliban leader Adnan Rashid was captured over the weekend in South Waziristan. Rashid, who was apparently injured during the recent fighting in North Waziristan, was caught as he tried to flee the area, the officials said.

Rashid had been arrested in 2004 on charges that he conspired to assassinate then-President Pervez Musharraf. In 2012, however, he escaped from prison with 400 other militants.

Last year, Rashid made international headlines when he wrote a letter to Malala Yousafzai expressing regret that a Pakistani Taliban militant shot her in 2012.

Yousafzai, who was 15 at the time of the shooting, was targeted after she began publicly pressing for more educational opportunities for girls in Pakistan’s western Swat Valley.

Aamir Iqbal in Peshawar, Pakistan, contributed to this report.