Bangalore, July 15: A petrol bomb thrown at a Protestant church weeks after road signs carrying Christian priests' names were vandalised has stoked concern in Tumkur, a largely peaceful city 80km north of Bangalore.

Thursday's pre-dawn attack on the 86-year-old Tomlinson Church singed the main door and parts of the wall before the caretaker doused the fire with local help. But the discovery of three empty beer bottles in a box under a nearby tree suggested a planned attack, police said.

Hundreds of Christians staged a silent sit-in outside the Town Hall in Tumkur today demanding the arrest of the lone attacker, seen in CCTV footage from the compound.

A man is seen trying and failing to push the gate open around 4.10am. He then lights the wick of a petrol-filled beer bottle and hurls it at the church door, about 15 metres from the gate.

The arsonist then seems to have lingered for a while, probably with more mischief in his mind, as the remaining three bottles suggest. He appears to have fled only after the caretaker, who lives next door and was woken by the thud of the bottle against the door, arrived on the scene.

"I saw him run away," caretaker Hanok, who uses just one name, said.

Hanok raised the alarm, attracting a few neighbours. "I got water from a tap on the church compound and doused the fire with the help of three local people," the caretaker said.

Tumkur additional superintendent of police G.B. Manjunath said a case of arson had been registered and teams formed to track down the man seen in the footage.

The only attack on a Tumkur church in recent memory happened in September 2007, when vandals broke into the Gregorious Church and damaged the altar and the sacred vestments. But in hindsight, some portents did appear less than a month ago.

On June 24, a concrete road sign on Reverend Sadedore Road was found demolished and a board displaying the name of Reverend Tomlinson Road was defaced. Both road signs had been installed by the civic body on June 19.

"We took the signboard incidents lightly and didn't file any police complaint," Jayabhushan, the secretary of the church who too uses just one name, said.

"But this looks quite serious as it's the third such attack on Christian interests in less than a month in Tumkur."

The Tomlinson Church, designed somewhat like a Hindu temple in a nod to local architectural style, had installed CCTV cameras four years ago after several churches came under attack in various parts of the country.

"Fortunately, the church door and the main gate were locked and our CCTV was functioning," Jayabhushan said.

"If our caretaker hadn't rushed out of his home, the attacker would have done something worse. There hasn't been much damage, but we see this as an attack on our peaceful community."

Church attacks have been more common in southern coastal Karnataka, especially Mangalore city, which witnessed a string of them in 2008. The latest came after a lull in February last year, with stone-throwing vandals damaging the grotto (the glass encasing of idols) at St Joseph Vaz Prayer Hall, Mangalore.

A few suspected Bajrang Dal activists were arrested for the Mangalore attacks but none has so far been convicted.