In a grim conclusion to the Muslim holy month of Ramadan, Syrian security forces killed at least seven protesters across the country Tuesday, activists said, as the United States announced new sanctions against top Syrian officials.

Security was heavy as thousands of people poured out of mosques to stage anti-government demonstrations after early morning prayers at the start of Eid al-Fitr, the three-day-long celebration that follows Ramadan.

The deaths came in the southwestern province of Daraa, where the protests began nearly six months ago, and in the restive central city of Homs, according to the Local Coordination Committees, an activist network.

Several people were injured in the capital, Damascus, and one person died Tuesday after being wounded during a protest there Friday, a Damascus-based activist said. The man’s funeral took place at midday, drawing large crowds in the city center, the activist said, speaking on the condition of anonymity for fear of reprisals.

An amateur video posted by pro-democracy activists shows protesters calling for the ouster and even death of Syrian President Bashar al-Assad. In the video, said to be filmed in a suburb of Damascus, protesters chanted, “The people want to execute the president.”

Security forces carried out a major crackdown on demonstrators throughout August, which coincided with Ramadan. After initially calling for political reforms, protesters have expanded their demands, increasingly calling for Assad’s ouster as the death toll has mounted. The Syrian Revolution Coordination Union, an activist group, says 551 people were killed during Ramadan; the United Nations has said that more than 2,200 people have been killed since protests started in March.

“It really escalated today,” said an activist in Damascus, contacted via Skype, who also asked for anonymity. “We saw mass protests where usually we would only see moderate protests.”

Assad performed Eid prayers Tuesday at the Hafez al-Assad Mosque in Damascus, according to SANA, the Syrian state news agency. The mosque is named after the president’s late father.

Since the government of Libyan leader Moammar Gaddafi fell last week, voices in the Syrian opposition demanding armed insurrection have grown louder. But the Local Coordination Committees, one of the largest groups, issued a statement Monday calling for the protests to remain nonviolent, and other groups have also appealed for calm.

“The Syrian people are looking for more international pressure, but not international intervention,” said a Damascus-based activist who uses the pseudonym Alexander Page to avoid detection.

“The government wants a rebellion,” he said via Skype. “They want it to start quickly so that they can kill all” the protesters.

Activists have called for minimal Eid celebrations this year in solidarity with the Syrians who have been killed or arrested. “There will be no happiness while the martyrs’ blood is still warm,” the Local Coordination Committees said in a statement Tuesday.

In an apparent bid by the government to prevent protesters from organizing on Tuesday, cellphone service was cut in many parts of the country and Internet access slowed. Even many satellite phones, usually the most reliable way to contact activists and eyewitnesses in Syria, seemed to be out of service.

The government has allowed few reporters into the country.

International pressure is mounting on Assad, with even longtime allies calling on him in recent days to undertake reforms. Turkey’s president, Abdullah Gul, said Sunday that his patience had run out. Iran’s foreign minister, Ali Akbar Salehi, said Syria’s government had to recognize the Syrian people’s “legitimate” demands.

Also Tuesday, the U.S. Treasury Department announced new sanctions against three top Syrian officials: Foreign Minister Walid al-Moualem, Assad adviser Buthaina Shaaban and Syria’s ambassador to Lebanon, Ali Abdul Karim Ali. The officials’ U.S. assets are restricted, and Americans are prohibited from doing business with them.

It was unclear whether the pressure would have an immediate effect on the Syrian government. Syria’s state news agency said that Assad had held a meeting Monday on “foreign interference in . . . internal affairs.”

Special correspondents Ingy Hassieb and Haitham Tabei contributed to this report.