Story highlights

The blasts target police officers

Two blasts occur within 15 minutes of each other

In another attack, gunmen shoot at a district police chief in Dagestan

CNN  — 

A series of attacks against police hit the Russian North Caucasus region of Dagestan on Thursday, killing several officers and injuring dozens more, authorities said.

An unidentified person set off a bomb equivalent to about 3 kilograms (more than 6 pounds) of TNT shortly after midnight near the police headquarters in the regional capital of Makhachkala.

No one was hurt, the local police department reported on its website.

Fifteen minutes later, when investigators arrived at the scene, a more powerful car bomb went off, killing a police officer. It injured 39 people, including 32 officers, police said.

Dagestan police said on its website that the second bomb had the power of 35-40 kilograms of TNT.

The Russian Interior Ministry reported on its website that the blast killed one police officer and injured 60 people, including 44 officers.

An investigation will be conducted, the Russian Investigative Committee said in a statement.

“Shops and residential buildings in the epicenter of the explosion were either damaged or completely destroyed,” it said.

Also Thursday morning, attackers in a car shot at a district police chief in the Dagestani city of Buinaksk .

Col. Magomednabi Adilkhanov was not injured, but two of his bodyguards were killed, local police reported.

A day before the attack on the police chief, three men died in a car explosion in Makhachkala. Police said the initial investigation suggests they mishandled a bomb during its transportation.

Several security officers were reported killed in Dagestan last week, as well as a mosque imam.

Following Russia’s two bloody wars in Chechnya against Islamist separatists in the 1990s, the militant insurgency spilled onto other neighboring regions in the area.

Dagestan is the largest and most volatile of the five Northern Caucasus regions. Rebels continue to stage frequent attacks on security forces, police and civilians, placing it at the center of the insurgency.

Last month, the head of the Federal Security Service Alexandr Bortnikov told the Russian president that in the first six months of this year, 169 terrorist acts were committed, of which 110 took place in Dagestan.

Ninety-five law enforcement officers died in those attacks, he said.

In the same time period, Bortkinov said, security officers arrested 400 rebels and their accomplices, and killed 250 more.