In this June 22, 2009 file photo, investigators work at the scene of a bomb explosion on the outskirts of Nazran. [Agencies]

NAZRAN, Russia: A suicide bomber exploded a truck at a police station in Russia's North Caucasus on Monday, killing at least 20 people and wounding about 60 others, officials said.

The bombing was the deadliest in months in the restive southern region, denting Kremlin claims that the area was stabilizing after 15 years of separatist fighting in Chechnya and violence in surrounding provinces.

The attacker rammed the gates of the Nazran city police headquarters, in Ingushetia province, and detonated his explosives as police officers were lining up for a morning check, said Svetlana Gorbakova of the regional branch of the Investigative Committee of the Russian Prosecutor General's office.

A nearby apartment building and several office buildings were also damaged, and burned-out cars littered the street.

At least 20 people were killed, Gorbakova said, though official figures on the number of wounded varied. Gorbakova said 57 people were hurt, including 10 in critical condition. Ruslan Koloyev, the acting head of the Emergency Ministry's branch in Ingushetia, said on Rossiya television that 92 people were injured.

An Associated Press reporter saw 11 badly burned bodies at a morgue in Nazran, the largest city in Ingushetia, which borders Chechnya to the west.

Local authorities announced a three-day mourning.

The attacker and the truck were pulverized by the blast, said Svetlana Gorbakova of the regional branch of the Investigative Committee of the Russian Prosecutor General's office.

While large-scale fighting from the two wars that ravaged Chechnya since 1994 has ended, Islamic militants continue to mount regular hit-and-run attacks and skirmishes. Bloodshed has surged in recent months and increasingly spilled into provinces neighboring Chechnya.