The Navy and police went on high alert after some local students reported that masked persons armed with guns were sighted in the coastal village of Karanja near Uran on the outskirts of Mumbai on Thursday.
Confirming the developments, an Indian Navy spokesman said: "The Navy is on a high state of alert after getting this input."
The Indian Navy, a team of the elite Force One, the Anti-Terrorist Squad, Maharashtra Police, Navi Mumbai police, Mumbai police, and other agencies were engaged in a joint operation to weed out the unknown armed persons with a potential to create mischief.
The first tip-off came from at least three-four school children of Uran Education Society's school who informed their teachers, who in turn alerted police and all other security agencies were quickly geared into action to counter the situation.
Maharashtra Director-General of Police Satish Mathur said two students had informed the police of sighting some suspicious men in Uran.
"While one student has claimed spotting one person, the other has claimed to have seen five. After this information, multiple agencies are probing it," Mathur said.
A defence spokesperson said that according to a report they received, early Thursday morning, five-six persons in Pathani suits were sighted and appeared to be carrying weapons and backpacks.
Some other reports claimed that they were attired in some kind of military uniforms, but that could not be officially verified.
The Western Naval Command reacted promptly by first sounding an alert and informing all coastal security agencies which are now on high alert in Raigad and the country's commercial capital, Mumbai, with its helicopters and patrol ships deployed in the vicinity.
"Searches and other actions as per procedures have been initiated. The situation is being closely monitored in liaison with the police. No person has been located or apprehended till now," the spokesperson said.
The news spread like wildfire in Uran and nearby areas, resulting in the closure of schools and colleges for the rest of the day.
The entire town of Uran went on a spontaneous shutdown as a precaution even as the Navi Mumbai Police Commissioner, district police and Navy officers went to the spot to verify the students' claims.
A similar high alert was sounded in Mumbai with armed police taking positions at various points in south Mumbai, including near the Gateway of India and Girgaum Chowpatty. All coastal police stations from Palghar to Goa have been alerted to keep a lookout for any suspicious activities.
While the police have launched a massive combing operation in Uran and surrounding parts of Raigad, in Mumbai, Navi Mumbai, Thane and other places, local police put up road-blocks to check all suspicious vehicles entering or exiting these cities.
Security has also been tightened at important places like Raj Bhavan, Mantralaya, important stations of the railways, the ports, airlines and other commercial offices in south Mumbai.
All agencies concerned are not taking the tip-off by the students lightly in view of last Sunday's terror strike in Jammu and Kashmir's Uri town, especially since the suspicious sightings have taken place near a naval training base for MARCOS (marine commandoes) in Uran on the mainland.
Besides, the entire region is highly sensitive in view of the close proximity of the Western Naval Command headquarters just across the harbour in Mumbai, the naval harbour, the Mumbai Port Trust, the Jawaharlal Nehru Port Trust, several critical installations like BARC and oil terminals, power plants and refineries, offices of important central and state government in a small radius.
The development brought back memories of November 26, 2008, when a group of 10 Pakistani terrorists had sneaked into Mumbai through the Arabian Sea at Colaba and then created mayhem for 60 hours.
Much earlier, the sea route was taken for landing large quantities of arms and ammunition at various points on the Maharashtra coast which were used for carrying out the serial bomb attacks in Mumbai on March 12, 1993.