Libyan leader Moamar Gaddafi has sent armoured forces into the coastal town of Zawiyah to reassert control but has run into rebel resistance.
Arab satellite television channels including Al Jazeera said tanks fired at residential buildings in Zawiyah, 50 kilometres west of the capital Tripoli.
"Now with all the artillery, tanks and armored vehicles, we're seeing battles and killings we haven't seen in Iraq," one witness told Al Arabiya television station.
"I consider it total genocide. The battles have now entered the city. More than 15 armoured vehicles entered two hours ago along with a tank.
"There is heavy firing in all the areas and mosques have announced jihad against these brigades."