BEIRUT (AP) — Heavy machine-gun fire erupted across the besieged Syrian city of Latakia on Tuesday as the death toll rose to 35 from a military assault now in its fourth day, residents and activists said.

President Bashar Assad has dramatically escalated the crackdown on a 5-month-old uprising since the start of the holy month of Ramadan. Despite broad condemnation, the regime is trying to retake control in rebellious areas by unleashing tanks, ground troops and snipers.

Assad has launched military operations in the opposition stronghold of Hama, the eastern city of Deir el-Zour, the central city of Homs and now the port city of Latakia.

Most of the shooting early Monday was in Latakia’s impoverished al-Ramel, al-Shaab and Ein Tamra areas. Al-Ramel is home to a crowded Palestinian refugee camp where many low-income Syrians also live.

The U.N. agency that aids Palestinian refugees said Monday more than 5,000 refugees have fled the camp after Assad’s forces shelled the city in an operation that began Saturday.

UNRWA said the Palestinians fled after the city came under fire from gunboats cruising off the coast and ground troops attacked over the weekend.

“We are calling for access to the camp to find out what is going on,” said UNRWA spokesman Chris Gunness. “There were 10,000 refugees in the camp and we need to find out what is happening to them.”

Syria has denied firing from gunboats, despite widespread witness accounts. The regime insists its crackdown is aimed at rooting out terrorists fomenting unrest in the country.

The London-based Syrian Observatory for Human Rights and the Local Coordination Committees, two activist groups with a network of people on the ground, said at least 15 people were killed Monday, five of them in Latakia.

Monday’s deaths bring the total of people who have died in Latakia since Saturday to around 35.

Also Monday, Turkey’s Foreign Minister Ahmet Davutoglu called on Syria to immediately end the bloodshed and threatened unspecified “steps” if it fails to do so.

“If the operations do not end, there would be nothing more to discuss about steps that would be taken,” Davutoglu said, without elaborating.

Turkey, a former close ally of Syria, has been increasingly frustrated with Damascus’ crackdown. Davutoglu traveled to Syria last week and urged Assad to end the bloodshed. But Turkey, Syria’s neighbor and an important trade partner, has not joined the U.S. and Europe in imposing sanctions.

In Washington, White House spokesman Jay Carney said Assad must “cease the systematic violence, mass arrests and the outright murder of his own people,” adding that the Syrian president “has lost legitimacy to lead.” Carney said the U.S. would be looking to apply further sanctions against Assad’s government.