Heavy clashes erupted across Syria on Saturday while government forces battled opposition fighters in various cities.

Here are the latest key developments in the nearly 18-month crisis:

On the ground: Shelling, ground battles rage on

At least 162 people died across Syria on Saturday, including 55 in and around Damascus, opposition activists said.

Several political activists reported that regime forces raided a hospital in the Damascus suburb of Kafar Batna, killed medical staff, and wounded patients. They said regime forces later burned the hospital.

The Local Coordination Committees of Syria, an opposition group, said the regime forces had targeted the hospital in the past because it treated protesters.

Rebel forces captured a military air force base to prevent airstrikes and shelling of civilians, a member of the opposition told CNN Saturday.

The opposition fighters laid siege to the air base for 11 days before raiding it, Ridha Al-Alwani said via Skype from the border city of Albu Kamal in Deir Ezzour province.

A Free Syrian Army spokesman confirmed taking control of the Air Defense battalion headquarters in Albu Kamal. The spokesman said the government was using the base to launch strikes against residential neighborhoods.

The military, however, still controls two other bases that it used to launch airstrikes following the rebel attack, Al-Alwani said.

In Damascus, heavy gunfire rang out as army tanks patrolled the capital, according to the opposition.

CNN cannot independently verify reports of violence, because the Syrian government limits access to international journalists.

The Syrian government: Detainees released

The Syrian government released 341 detainees on Saturday, according to the state-run Syrian Arab News Agency (SANA). It reported those released were "citizens who got involved in the recent events in the country but did not shed blood."

The detainees pledged not to repeat the acts they had committed, SANA reported.

"A number of the released stressed they will stand in support of the homeland and the exerted efforts aimed at rebuilding it and consolidating its strength," the news agency said. "They saw their release as a new start for them to go back to their normal life."

The region: Turkey wants a no-fly zone

Turkish Prime Minister Recep Tayyip Erdogan on Saturday called on the U.N. Security Council to declare a no-fly zone along the Turkey-Syria border.

"The region should be declared a no-fly zone first, and then we can take a step for a buffer zone," he told the Anatolian news agency.

He also said there are now more than 80,000 Syrians now in Turkey because of the crisis.