Within 24 hours of an attack by two drones at an Indian Air Force (IAF) station in Jammu, two similar devices were spotted hovering over the Ratnuchak-Kaluchak military area in the region, prompting soldiers to open fire at them, officials said on Monday.

Experts say a new security threat has emerged from across the border with Pakistan, with drones being used for the first time to carry out attacks at military installations. Early on Sunday, drones were used for two “low-intensity” explosions at the IAF station in Jammu, leaving two personnel injured and prompting multiple teams to launch investigations.

On Sunday night, two more drones were spotted over the military stations. While the first drone was sighted around 11.45pm, the second one was seen around 2.40am.

Defence spokesperson Lt Col Devender Anand said soldiers opened fire at the two drones but they flew away. “On midnight of 27-28 June, two separate drone activities were spotted over Ratnuchak-Kaluchak military areas by alert troops. Immediately, high alert was sounded and quick reaction teams engaged them with firing. Both the drones flew away,” Anand said.

“Searches were launched… and we are also ascertaining whether they were being operated from a vehicle on the adjoining road,” he said, adding a “major threat was thwarted” because the troops were alert.

Hours before the incident, the first blast at the Jammu airport, which is used for VVIP movement and armed forces’ strategic operations, took place at 1.37am, causing minor damage to the roof of a building, and the second one – said to be weaker in intensity – was reported at 1.42am in an open area.

The air force has beefed up air defence at its forward airbases in the western sector to pre-empt fresh drone attacks, people familiar with the developments said on Monday. While IAF is now certain that drones were used for the Jammu attack, it is still not clear as to where they came from or which side they flew to after dropping the two improvised explosive devices, an official said on condition of anonymity.

There have been several incidents of Pakistan-based terrorists using drones in the border areas of Jammu and Kashmir to drop arms, ammunition, drugs and money to fuel terrorism in the region. But experts said that drones have previously not been engaged by terrorists to carry out attacks.

The Kaluchak military station was attacked in 2002 by three armed terrorists from Pakistan. The three first attacked a Himachal Road Transport Corporation bus on the Jammu-Pathankot highway and killed seven passengers before storming the station, where they killed 23 people.

At least 300 drones have been sighted along the border with Pakistan since the 2019 abrogation of Article 370, a security official told PTI on Monday. Border security agencies have been testing indigenously built counter-drone technologies in the rough jungle terrains, desert and marshes along the western front but have had limited success, the official said.

Chief of defence staff General Bipin Rawat on Monday told a TV channel that the three services, the Defence Research Development Organisation (DRDO), academia and other stakeholders were working together to develop technology to counter the threat from drones at the earliest.

The second incident of the spotting of drones on Sunday led to the area outside the military stations being cordoned off. A massive search operation was still underway on Monday night. No debris was found on the ground, a person aware of the operation said.

The incidents come days after Prime Minister Narendra Modi told political leaders from Jammu and Kashmir that elections would be held there once delimitation is carried out, two years after the special status of the erstwhile state was revoked.

Following a series of back-channel contacts between Indian and Pakistani security officials, the two countries recommitted themselves to the 2003 ceasefire on the Line of Control (LoC) in February. The truce has largely held, helping to ease bilateral tensions, though recent reports have suggested the back-channel contacts have stalled.

Pakistan has also issued several strong statements in recent weeks about what it claims were the Indian government’s plans to carry out more changes in Jammu and Kashmir. India has rejected these statements, noting that Kashmir is an integral part of the country and Pakistan’s comments amounted to interference in internal affairs.