A hand grenade was hurled at the Kalimpong police station at around 11 pm last night, killing a civic volunteer and injuring two others. The injured were subsequently hospitalised.
An initial probe has revealed that bike-borne miscreants had hurled the grenade at the police station, the police said, adding that they were going through the CCTV footage to get more clues.
In another incident, a high-intensity explosion rocked the Chowkbazar area of Darjeeling town in the early hours yesterday.
Additional Director General of Police (law and order) Anuj Sharma said Gorkha Janmukti Morcha (GJM) supremo Gurung and others had been booked under the UAPA in connection with the two blasts.
"We have also slapped charges under the Explosive Substances Act, the West Bengal Maintenance of Public Order Act, section 302, IPC (punishment for murder) and other sections against Mr Gurung and others," he added.
Meanwhile, a Gorkhaland Territorial Administration (GTA) office was set on fire allegedly by Gorkhaland supporters at Kalimpong last night.
The situation in Darjeeling remained tensed as the indefinite strike called by the GJM, demanding a separate state of Gorkhaland, entered its 67th day today.
The grenade attack on the Kalimpong police station and the blast in Darjeeling town were the first such incidents since the indefinite strike began over two months ago.
"We are monitoring each and every entry and exit point. A forensic team will visit the police station," a senior police officer said.
The GJM leadership, however, condemned the attack on the police station.
"We condemn the grenade blast at the police station. It is the handiwork of those who do not want Gorkhaland to be formed," a senior leader of the party said.
After yesterday's blast at Chowkbazar, Mr Gurung had written a letter to Union Home Minister Rajnath Singh, demanding a high-level inquiry by the National Investigation Agency (NIA) into it.
West Bengal Tourism Minister Gautam Deb said those behind the blasts would not be spared and the law would take its own course.
As the police conducted an area domination march in the hills today, none of the political parties took out any rally.