SECURITY FORCES OPENED fire Friday on demonstrators trying to break an army blockade on the southern city of Daraa, while thousands of others across Syria defied a protest ban and denounced President Bashar Assad’s harsh crackdown on a six-week uprising. At least 42 people were killed, including 15 in the march on Daraa, according to witnesses and a human rights group.

The protesters in cities across Syria — including the capital of Damascus — called for Assad’s ouster, with some chanting “We are not afraid!”

Human rights activist Mustafa Osso said 42 people were killed, but the death toll could rise. His human rights group, based in Syria, compiles casualty tolls from the crackdown.

A witness in Daraa — the heart of the uprising — said residents stayed indoors because the city has been under siege by the military since Monday, when thousands of soldiers backed by tanks and snipers stormed in. People were too afraid even to venture out to mosques for prayers, the witness said.

“We are in our houses but our hearts are in the mosques,” the witness said, speaking by satellite telephone and asking that his name not be published for fear of reprisals.

Large demonstrations broke out in Damascus, the central city of Homs, the coastal cities of Banias and Latakia, the northern cities of Raqqa and Hama, and the northeastern town of Qamishli.

In Damascus’ central Midan neighborhood, witnesses said about 2,000 people marched and chanted, “God, Syria and freedom only!” in a heavy rain, but security forces opened fire with bullets and tear gas, scattering them.

“Oh great Syrian army! Lift the blockade on Daraa!” protesters chanted in the Damascus suburb of Barzeh, according to video footage posted by activists on YouTube.

The government had warned against holding any demonstrations Friday and placed large banners around the capital that read: “We urge the brother citizens to avoid going out of your homes on Friday for your own safety.” Syrian TV said the Interior Ministry has not approved any “march, demonstration or sit-in” and that such rallies seek only to harm Syria’s security and stability.

Since the uprising in Syria began in mid-March, inspired by revolts across the Arab world, more than 450 people have been killed nationwide, activists say.

Assad’s attempts to crush the revolt — the gravest challenge to his family’s 40-year ruling dynasty — have drawn international criticism.

The U.S. hit three top Syrian officials, Syria’s intelligence agency and Iran’s Revolutionary Guard with sanctions. The sanctions affect Maher Assad, Assad’s brother and commander of the Syrian Army’s Fourth Armored Division, which is accused of carrying out the worst atrocities in Daraa; Assad cousin Atif Najib, the former head of the Political Security Directorate in Daraa Province; and intelligence chief Ali Mamluk, the White House said.

Although Assad himself is not among those hit with sanctions, officials said he could be named at a later date if the crackdown continues.

Assad’s government says the protests are a foreign conspiracy carried out by extremist forces and armed thugs, not true reform-seekers.

Syrian TV said military and police forces came under attack Friday by “armed terrorists” in Daraa and the central city of Homs, killing four soldiers and three police officers. Two soldiers were captured, the report said. The station also said one of its cameramen was injured in Latakia in an attack by an armed gang.

Outside Homs, thousands chanted “We don’t love you!” and “Bye, bye Bashar! We will see you in The Hague!” as the sound of gunfire crackled in the distance.

A devastating picture was emerging of Daraa — which has been without electricity, water and telephones since Monday — as residents flee to neighboring countries. Daraa is where the uprising kicked off, sparked by the arrest of teenagers who scrawled anti-regime graffiti on a wall.

Residents inside the city begged for international intervention Friday.

“Nobody can move in (Daraa), they have snipers on the high roofs,” a resident told The Associated Press using a satellite phone. “They are firing at everything.”

- AP