GROZNY, Russia (Reuters) - A suicide bomb blast that killed at least four interior ministry soldiers and injured others in the capital of Russia's volatile Chechnya region on Monday may have been organized by Islamist militants, regional leader Ramzan Kadyrov said.
The explosion, which Interfax news agency said happened as the soldiers left an armored vehicle near their garrison quarters, shattered the fragile peace of the broader North Caucasus region, where militants trying to create an Islamist state carry out daily violence.
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.
Kadyrov said brothers Muslim and Khuseyn Gakayev were possible organizers 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 of the two suicide bombers had been identified.
"According to information, 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 of aiding members of illegal armed groups," Kadyrov said on his government's website.
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 split from an insurgency headed by Russia's most wanted man Doku Umarov in 2010, but returned to Umarov's fold last year, swearing loyalty to the Chechen-born militant, who styles himself the Emir of the Caucasus.
Umarov 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.
Compared with the rest of the North Caucasus, violence has been rare in Chechnya where Kremlin-backed leader Ramzan Kadyrov has used strong-arm tactics to clamp down on the insurgency.
Locals and human rights workers say such methods, along with religious extremism and corruption, have added fuel to the violence, which is rooted in two wars that Moscow has fought against separatists in Chechnya between 1994-2000.
The focus of the violence has since moved to the neighboring region of Dagestan.
(Writing By Nastassia Astrasheuskaya and Thomas Grove; Editing by Sophie Hares)
(This story corrects reference to Gakayev's relationship with Umarov and clarifies sourcing)