BEIRUT (AP) ― Syria used gunboats for the first time Sunday to crush the uprising against Bashar Assad’s regime, hammering parts of the Mediterranean coastal city of Latakia after thousands marched there over the weekend to demand the president’s ouster. At least 25 people were killed, according to activists.

The coordinated attacks by gunboats and ground troops were the latest wave of a brutal offensive against anti-government protests launched at the beginning of the month. The assault showed Assad has no intention of scaling back the campaign even though it has brought international outrage and new U.S. and European sanctions.

“We are being targeted from the ground and the sea,” said a frightened resident of the al-Ramel district of Latakia, the hardest hit neighborhood. “The shooting is intense. We cannot go out. They are raiding and breaking into people’s homes,” he added, speaking on condition of anonymity for fear of reprisals.

As the gunships blasted waterfront districts, ground troops backed by tanks and security forces stormed several neighborhoods including al-Ramel, sending terrified women and children fleeing, some on foot, to safer areas.

The al-Ramel resident said at least three gunboats were taking part in the offensive, and that many people have been killed and wounded. The shooting targeted several mosques in the area.

“Many homes have been destroyed and the shabiha have broken into shops and businesses,” he said, referring to pro-government gunmen, as they are called by Syrians.

The assault on Latakia began Saturday, when tanks and armored personnel carriers rolled into al-Ramel district amid intense gunfire. The security forces appear to be intent on crushing dissent in the neighborhood, which has seen large anti-Assad protests since the Syrian uprising began in mid-March. On Friday, as many as 10,000 marched there, calling for the president’s ouster.

After their initial assault on the city Saturday, Syrian forces pushed back into Latakia again Sunday.

State-run news agency SANA said troops were pursuing “gunmen using machine guns, hand grenades and bombs who have been terrorizing residents in al-Ramel district.” The agency denied reports the area was being targeted from the sea. It quoted a health official in Latakia as saying two law enforcement officials were killed.

At least 25 people were killed in the city on Sunday, said Rami Abdul-Rahman, head of the London-based Syrian Observatory for Human Rights. One of the dead was a 2-year-old girl who was in a car with her father when security forces at a checkpoint opened fire, he said. The activist network the Local Coordination Committees gave the same death toll and said it included three children.

Activists said at least two people were killed in al-Ramel on Saturday.

Residents and several activist groups said gunboats in the Mediterranean were taking part in the offensive, firing machine guns. Many people were wounded from indiscriminate fire on houses, they said.

“They are trying to take control of the city as they did in other places,” said Abdul-Rahman.

Ammar Qurabi, head of the National Organization for Human Rights in Syria, said the state was setting a “precedent” by using gunboats to shell its own people.

Using gunboats to fight protesters, who are most unarmed and peaceful, marks a new escalation in the regime’s crackdown. But the determined opposition is so far unbowed even though at least 1,700 people have been killed since March, according to activists and human rights groups.

The tough new offensive began with the Muslim holy month of Ramadan at the start of August and killed several hundred people in the first week alone.

The brutality fueled international outrage with Syria, a hardline Arab state closely allied with Iran, and led to new sanctions against the regime by the U.S., Canada and Europe.

The United States stepped up calls for a global trade embargo on oil and gas from Syria, warning even some of America’s closest allies that they must “get on the right side of history” and cut links with a government that uses violence to repress protesters.

Secretary of State Hillary Rodham Clinton said international opinion was hardening against Assad, noting a “crescendo of condemnation” from world powers and Syria’s Arab neighbors. But she said tougher action was required, too.

In Latakia on Sunday, the sharp crackle of machine-gun fire and loud explosions sounded across parts of the city, once known for its beach resorts that attracted tourists throughout the summer season. Gray smoke drifted across the sea front.

The city has a potentially explosive sectarian mix. Sunnis, which are a majority in Syria, live in Latakia’s urban core, while Assad’s minority Alawite sect, an offshoot of Shiite Islam, populates villages on the city’s outskirts, along with small minorities of Christians, ethnic Turks and other groups.

The crackdown, which has targeted predominantly Sunni areas of the city of more than 600,000, raised concerns of sectarian bloodshed in a country that has already seen an alarming rise in sectarian tensions since the start of the uprising.

Amateur videos posted on the Internet by activists showed at least one gunship patrolling the coast opposite al-Ramel, and tanks rumbling along the waterfront.

The Associated Press could not verify the activists’ accounts or the contents of the videos. Syria has banned most foreign media and restricted local coverage, making it impossible to get independent confirmation of the events on the ground.

The protests calling for the Assad regime’s downfall have grown dramatically over the past five months, driven in part by anger over the government’s bloody crackdown.

Thousands of others have been arrested, many of them tortured, according to rights groups.

The Observatory said in a statement Sunday that it has documented the names of 71 Syrians who have died under torture in Syria since the start of the uprising in mid-March.

The government has justified its crackdown by saying it’s dealing with terrorist gangs and criminals who are fomenting unrest.