GROZNY, Russia (Reuters) - A suicide bomb blast that killed at least four soldiers and injured three other people in the capital of Russia's volatile Chechnya region on Monday may have been organised by an Islamist militant group headed by two brothers, a regional official said.
The explosion, which Interfax news agency said happened as the soldiers left an armoured vehicle near their garrison quarters, shattered the fragile peace of the broader North Caucasus region, where militants trying to create an Islamist state still use violence daily.
Grozny residents said they heard two explosions, the second of which sent flames and smoke into the air. A Reuters witness saw the remains of three people in camouflage clothing lying at the roadside after the blast.
Regional head Ramzan Kadyrov said brothers Muslim and Khuseyn Gakayev were possible organisers of the attack and said they had previously orchestrated similar suicide bombings.
"This is the Gakayevs' tactics - to find sick and mentally deficient people, stuff them with narcotics and send them to die," Kadyrov told journalists while visiting the blast scene.
He said one two suicide bombers had been identified.
"According to the latest update, the terrorist act was carried out by two suicide bombers. The identity of one of the terrorists has been determined. He has previously been convicted for aiding members of illegal armed groups," Kadyrov was quoted by Interfax as saying.
Kadyrov said law enforcement agencies had been instructed to track down and arrest the Gakayev brothers, using force if necessary, adding they know "the loop is tightening around them".
Khuseyn Gakayev was formerly a commander under Doku Umarov, the leader of a separate Islamist insurgency who claimed responsibility for a suicide bombing at Moscow's Domodedovo airport that killed 37 people in January 2011, and twin bombings that killed 40 people in the Moscow metro in 2010.
Khuseyn Gakayev broke away from Umarov at the end of 2010 and set up an alternate Islamist movement with his brother Muslim.
Moscow has fought two wars against separatists in Chechnya since 1994.
Compared with the rest of the North Caucasus, violence has been rare in recent years in Chechnya where Kremlin-backed leader Kadyrov has used strong-arm tactics to clamp down on the insurgency.
(Writing By Nastassia Astrasheuskaya and Thomas Grove; Editing by Sophie Hares)