Kolkata, July 17 (IANS) : Roads were blocked, buses damaged and government offices ransacked as parts of West Bengal Friday observed a dawn-to-dusk shutdown called by the Congress party to protest against a violent attack on its legislators this week. The Congress said the strike was "spontaneous" and "historic", but the ruling Left Front criticised it for "atrocious acts".

"The shutdown was completely successful and spontaneous. We received unprecedented response from across the state," state Congress working president Subrata Mukherjee told a press conference.

"The strike was observed more or less in a peaceful manner, except a few sporadic incidents," he said.

The strike was called in 12 of the state's 19 districts after a 14-member delegation led by Congress Legislative Party (CLP) chief Manas Bhuinya was attacked, allegedly by the Communist Party of India-Marxist (CPI-M) supporters, when they went to Dhanyarukhi village in Burdwan district Wednesday.

They had gone to distribute relief material among party supporters whose houses were burnt after the June 16 murder of CPI-M district committee member Falguni Mukherjee. Seven journalists accompanying the Congress delegation were also injured.

Demanding immediate administrative action to restore peace and normalcy in Mongolkote area of Burdwan district, Mukherjee said the state government would have to look into the issue and provide help to those people who are staying at temporary relief camps in the violence-scarred region.

"We'll soon visit Mongolkote with relief materials once again. And if we are again stopped, we will go for a bigger state-wide protest," he said, adding that the strike had largely affected the IT sector, tea industry, transport and railways.

State ruling Left Front chairman Biman Bose criticised the Congress for "atrocious acts" in the name of the strike.

"Patients were deprived of life saving medicines in Jalpaiguri district as the medical stores were forcibly closed by the supporters of shutdown. Tourists' luggage was also thrown out in Alipurduar station, where they took a halt while travelling.

"Congress activists also tried to snatch a convict from the police custody at Chashmore on way from Joypur to Purulia district," Bose said.

"Passengers of Gaya Passenger Train were also stopped by the Congress activists to alight on the Sreerampore station when the train halted there for while," he said.

According to reports, a group of enraged Congress supporters vandalised the head post office in Siliguri town of Darjeeling district.

"We've received a report that the head post office in Siliguri was vandalised by some political activists today morning. Another group of people, who were supporting the shutdown, also damaged the wind screens of a government bus in the same town," state Inspector General of Police (North Bengal) K.L. Tamta told IANS.

"At least four people have been arrested so far in connection with these two protests in Siliguri," he said.

Shops, schools, factories, offices remained closed and vehicles also kept off the roads as the supporters of the strike waving party flags took to the streets.

"The number of public transport was noticeably low in and around Kolkata. We had issued a notice to all state government departments to keep their regular service on. But it was somehow affected due to the strike," state Chief Secretary Ashok Mohan Chakraborty said.

Train services were paralysed while some airlines rescheduled or cancelled their flights.

Many long-distance and local trains were halted midway by protesters. A number of trains -- like Biswabharati Fast Passenger, Asansol-Haldia Express, Howrah-Purulia Express and Steel Express -- were stopped at different railway stations as Congress supporters squatted on tracks.

"Both Howrah-New Delhi and Sealdah-New Delhi Rajdhani Express trains were rescheduled following the strike," Eastern Railway spokesperson Samir Goswami said.

Police said a long-distance bus was damaged by mobs at Baguihati near the airport here.

"Four people were detained when they were trying to shut the Metro Railway station gate at Kalighat," Kolkata Police deputy commissioner (detective department) Jawed Shamim told IANS.

Attendance in IT and outsourcing firms here was also affected, officials said.