MOSUL, Iraq — Heavy fighting erupted in the eastern neighborhoods of Mosul today as Iraqi special forces launched an assault deeper into the urban areas of the city and swung round to attack Islamic State militants from a second entry point.

Columns of armored vehicles wound through open desert to open the new front, pushing through dirt berms, drawing heavy fire and calling in airstrikes to enter the middle class neighborhoods of Tahrir and Zahara. The area was once named after former Iraqi dictator Saddam Hussein.

Lt. Col. Muhanad al-Timimi said militants in separate explosives-laden vehicles tried to attack the troops but were destroyed.

The Islamic State group is fighting to hold Mosul as Iraqi forces and allied Kurdish troops squeeze in from all directions with U.S.-led coalition support.

Mosul is the last major IS stronghold in Iraq, and expelling the militant group from it would be a major blow to the survival of its self-declared “caliphate” that stretches into Syria.