At least 19 people have been killed in the Chechen capital of Grozny as Russian security forces battled with separatist militants, the Associated Press reported. The fighting, during which troops stormed two buildings, including a school, "punctured the patina of stability" Moscow aims to portray in the North Caucasus republic, the news service noted.

The incident occurred just hours before Russian President Vladimir Putin gave his annual state-of-the-nation address, in which he said he was confident that local Chechen forces were capable of dealing with the "rebels." The fighters are receiving support from abroad, Putin suggested.

The state-funded Russian television channel RT said nine of the casualties were militants, while 10 were law-enforcement officers. It described the battle as an "anti-terrorist operation."

Separatists traveling in three cars entered Grozny at 1 a.m., killing three traffic police at a checkpoint, Russian authorities told the Associated Press. The militants went on to occupy a 10-story building in the center of the city. Six gunmen were killed inside the structure, which was gutted in a fire that spread to a nearby market, according to the National Anti-Terrorist Committee.

Security forces later attacked a local school, where more gunmen were found, the AP added. No students or teachers were present, and state television showed footage of officers firing automatic weapons and grenade launchers at the three-story building.

Moscow-backed Chechen leader Ramzan Kadyrov, in Moscow for Putin's address, said the security operation was completed.

"I ask residents in areas where the operation is being carried out to take precautions, and (to) not to go outside without urgent need, nor to approach the windows," Kadyrov instructed local residents, according to RT. "All the talk about the city being under the control of militants is absolutely false."

Unrest is common in Chechnya, a largely Muslim region, the AP noted. But "forceful security measures adopted by Kadyrov spared Grozny significant violence for several years," the news agency said. Putin, meanwhile, has said trumpeted Russia's success in subduing Islamic separatists after years of war, a conflict which has claimed hundreds of thousands of victims.