MAKHACHKALA: A police convoy hit a bomb in Russia's restive North Caucasus, killing one person and wounding four others, a Russian official said Wednesday.

Fatina Ubaydatova, police spokeswoman in the restive region of Dagestan, said the convoy hit a bomb on the road south of the regional capital of Makhachkala on Tuesday evening. The convoy was ferrying federal police forces to the region. Police are sent to Dagestan on a regular basis to supplement local forces.

The Aamaq news agency, affiliated with the Islamic State group, said on Wednesday that IS fighters carried out the attack. The claim could not be immediately verified.

Later in the day, investigators at the scene found three more explosive devices planted on the side of the road on which the convoy was traveling.

Russian state television showed footage of the scene Wednesday and said one of the bombs is believed to have contained an equivalent of 5 kilograms (11 pounds) of TNT.

Dagestan has been the epicenter of an Islamic insurgency in Russia following two separatist wars in the neighboring region of Chechnya. For more than a decade, Dagestan has seen bombings, attacks on police and kidnappings blamed on the Islamic militants. But violence subsided significantly as law enforcement agencies clamped down on extremists ahead of the 2014 Winter Olympics in Sochi, and many militants are believed to have left for Syria to fight alongside Islamic State extremists.

Nearly a third of the estimated 3,000 Russians who are believed to have gone to fight in Syria against the government there are from Dagestan.