"Currently the police and army are patrolling the streets," he said "There are no helicopters or heavy armored vehicles."
He said the militants had been dressed like civilians and concealed their guns under their clothes. "With the current panic in the city, they are mixing in with other people, moving to different locations and then resuming random shooting on the streets, including firing at civilians," he added.
The source said policemen had been wounded.
The shooting started in the north of the city and then spread to other parts, he said. "I suppose there could have been several [armed] groups," he added.
The source confirmed that the militants had attacked the city's main police department and had broken into an arms depot.
The militants also blew up a base station belonging to mobile phone operator MegaFon.
