Pakistan’s air defense system shot down an Indian drone early Thursday near a naval air base in the eastern city of Lahore, Pakistani police and security officials said, as India evacuated thousands of people villages near the two countries’ highly militarized frontier in the disputed region of Kashmir.

The incident comes amid a crisis triggered a day after India launched strikes in Pakistan’s Punjab province and Pakistan-controlled Kashmir that killed 31 civilians, including women and children, according to Pakistani officials.

Tensions have escalated since April 22, when gunmen killed 26 people, mostly Indian Hindu tourists, in India-controlled Kashmir. India accused Pakistan of backing militants who carried out the attack, something Islamabad has denied.

Local police official Mohammad Rizwan said only that a drone was downed near Waltan airport, a small airfield in a residential area of Lahore that also contains military installations, about 25 kilometers (16 miles) east of the border with India.

Local media reported that two additional drones were shot down in other cities in Punjab province, of which Lahore is the capital.

Two security officials say a small Indian drone was taken down by Pakistan’s air defense system, speaking on condition of anonymity because they were not authorized to speak to media. It was not immediately clear whether the drone was armed.

The incident could not be independently verified, and Indian officials did not immediately comment.

India said its strikes Wednesday targeted at least nine sites in Pakistan linked to planning terrorist attacks against India.

In response, Pakistan’s air force shot down five Indian fighter jets, its military said.

Pakistani Prime Minister Shehbaz Sharif vowed overnight to avenge the killings but gave no details, raising fears of a broader conflict between the two nuclear-armed neighbors.

Across the de-facto border in Indian-controlled Kashmir, tens of thousands of people slept in shelters overnight, officials and residents said Thursday.

Indian authorities evacuated civilians from dozens of villages living close to the highly militarized Line of Control overnight while some living in border towns like Uri and Poonch left their homes on their own, three police and civil officials said. They spoke on condition of anonymity in keeping with departmental regulations.