Calcutta airport faced a security scare this weekend with armed guards in pursuit of an intruder sprinting down the tarmac after jumping off a taxi and entering the restricted area through a gate meant for authorised vehicles.

Till he was pinned down and declared a mentally unstable person trying to run away from his family, Pintu Kumar Singh, 25, was every bit a potential terrorist. After all, he had dodged three guards — two stationed at the gate and another in the sand bunker — to sprint 500 metres past them and come within less than 100 feet of a row of parked aircraft.

“An inquiry has been ordered. We will take strong action against the guards who were on duty,” Jayati Ghosh, the CISF commandant at the airport, told Metro on Sunday.

Pintu, from Murera village in Bihar’s Gopalganj district, had been refused entry into Thailand because of his allegedly abnormal behaviour and put on a flight back to the city on Saturday. Some relatives were escorting him back from the airport around 11.10pm when he opened the door of the taxi and jumped off.

“Pintu had gone to Bangkok on February 4 as a goods carrier for his employer. He was to return to the city on February 13 but he didn’t make it beyond the immigration counter at Bangkok airport,” an official said.

The immigration authorities apparently held him back on suspicion that he might be suffering from mental instability. “His passport and visa were in order. So his behaviour was the only reason not to allow him entry. He was visiting Bangkok for the first time,” the official said.

By the time one of the Calcutta guards spotted Pintu go past them on Saturday night — gate number four had been opened to let a vehicle pass — he was headed for the primary runway. The relatives who were running after him were stopped at the gate.

The guards later told officials that they did not fire at the intruder because his relatives pleaded with them not to, saying he was a mentally unstable man.

As the guards chased Pintu, the pilot of a Kingfisher Airlines flight from Hyderabad that had just landed spotted him at the crossing of the Golf and Fox taxiways.

“The pilot immediately informed air traffic control about the intruder in the apron area and also alerted the airline’s security staff,” said an official.

Two Kingfisher guards then joined the CRPF men in the chase, but Pintu was proving difficult to catch.

“When the guards caught up with him, he pushed two of them to the ground. It was only after the CISF’s quick-reaction team arrived that he could be pinned down,” an official said.

After a preliminary interrogation, Pintu was taken to the airport police station, where he again turned violent.

“He was suffering from extreme anxiety and looked scared when he was not violent. He seemed to be wanting to run away from his family members,” said a doctor who examined him.