In what is the first time Pakistan-based terrorists have used drones to strike vital installations, two bombs were dropped at the Indian Air Force station in Jammu airport in the early hours of Sunday, officials said.
Two Indian Air Force personnel were injured in the explosions that took place around 1.40 am within six minutes of each other.
The first blast ripped off the roof of a single-storey building at the high security technical area of the airport manned by the IAF in Satwari area on the outskirts of the city. The second one was on the ground, the officials said.
"The attack at the IAF station in Jammu is a terror attack," Jammu and Kashmir police chief Dilbag Singh told PTI.
He said the police and other agencies were working with IAF officials to unravel the plan behind the attack.
A team from anti-terror probe agency National Investigation Agency (NIA) was also at the spot.
It was not immediately clear from where the drones had taken off and investigations were on to ascertain their flight path, officials said.
Investigators scanned CCTV footage, including from cameras installed on the boundary walls of the airport, in an effort to determine from where the drones came.
However, all the CCTV cameras focused on the roadside, officials said.
Drones cannot be detected by radars deployed at border areas to monitor enemy activity, they said, suggesting that a different radar system that can detect drones as small as a bird be installed.
The drones dropped the explosive material and were either flown back across the border or to some other destination during the night, the officials said.
The aerial distance from the Jammu airport to the international border is 14 km.
While officials were investigating the drone attack, another major strike was averted when a person, probably owing allegiance to the banned Lashker-e-Tayiba, was arrested along with an improvised explosive device (IED) weighing around 6 kg, the director general of police said.
"The suspect has been detained and is being interrogated. More suspects are likely to be picked up in this foiled IED blast attempt," Singh said.
Officials said three more people have been rounded up for questioning.
Giving details of the person detained with the IED, the officials said he belongs to Banihal area in Jammu region and was tasked with planting the IED in a crowded place before getting enrolled in a terror group.
Defence Minister Rajnath Singh's office said he spoke to Vice Air Chief, Air Marshal H S Arora, over the airport incident.
In a Twitter post, the IAF said two 'low-intensity explosions' were reported early Sunday morning in the technical area of Jammu air force station.
'One caused minor damage to the roof of a building while the other exploded in an open area. There was no damage to any equipment. Investigation is in progress along with civil agencies,' it said.
Earlier in the morning, a defence spokesperson said, "There were reports of an explosion inside Air Force Station Jammu. There is no injury to any personnel or any damage to any equipment. Investigation is on and further details are awaited".
Jammu airport is a civil airport with the runway and the ATC (air traffic control) under the IAF.
Jammu Airport director Pravat Ranjan Beuria told PTI that there was no disruption in flight operations due to the explosions.
"Flights to and from Jammu airport are operating as per schedule," he said.
Jammu and Kashmir Police has registered an FIR under the Unlawful Activities (Prevention) Act, officials said, indicating that the case is likely to be taken over by the NIA.
"The NIA is already supervising the investigation at the scene of the blast after joining the probe," one of the officials said.
The FIR was also registered under relevant sections of the Explosive Substances Act and the Indian Penal Code at the Satwari police station on the application of a junior warrant officer of the IAF, he said.