Hundreds of Damascus residents fled from clashes and army shelling of several districts of the embattled Syrian capital Thursday, a rights watchdog reported, as the military gave them two days to get out.

The military said residents have 48 hours to leave areas where clashes are taking place between security forces and rebels, a security source told Agence France Presse.

Syria is not on track for peace and violence is escalating, the chief of the U.N. monitoring group said on Thursday, as clashes rocked Damascus and a day after three top regime officials died in a bombing.

"It pains me to say, but we are not on the track for peace in Syria, and the escalations we have witnessed in Damascus over the past few days is a testimony to that," Major General Robert Mood, head of the U.N. Supervision Mission in Syria, said in a statement to reporters.

Bahraini police said they had arrested another among a group of 20 people wanted over "terror attacks" in the kingdom, where authorities frequently crack down on Shiites taking part in protests.

Bahraini police had earlier announced the arrests of five other people on the list of suspects.

A car bomb on Thursday killed the police chief of Yemen's southern city of Aden when he was on his way to office, a police official said, accusing al-Qaida of carrying out the attack.

Colonel Abdullah al-Mouzai, the head of the police in Aden, "was killed when a device placed in his car exploded," the police official said, adding that the blast occurred when the police chief left home for his office.

More than 200 people, mostly civilians, were killed on Wednesday in violence across Syria, including 38 in Damascus where armed rebels are pressing an all-out offensive, a monitoring group said.

At least 214 people -- 124 civilians, 62 soldiers and 28 rebels died in one of the bloodiest days of a 16-month revolt against President Bashar Assad's regime, the Syrian Observatory for Human Rights said on Thursday, revising an earlier toll.

U.S. defense officials have held talks with their Israeli counterparts over whether Israel might strike at Syria's weapons facilities as its regime faces possible collapse, the New York Times reported.

The Times on Wednesday cited officials as saying that the Pentagon is not advocating military action because it feels that such an attack would help Syrian President Bashar Assad rally support against foreign intervention.

U.N. chief Ban Ki-moon and international envoy Kofi Annan called on the U.N. Security Council to take strong action on the Syria conflict ahead of a vote Thursday on a western-backed resolution calling for sanctions.

Russia and China are expected to veto the resolution at the 15-nation council despite mounting global concern over Syria after a Damascus bomb attack in which three close associates of President Bashar Assad were killed.

Bulgaria said Thursday a suicide bomber dressed as a tourist and with fake U.S. ID was behind an attack on Israelis on the Black Sea that killed seven people and left two in a coma.

U.S. President Barack Obama called the attack on a bus at Burgas airport on Wednesday, the deadliest against Israelis abroad since 2004, a "barbaric terrorist attack."

Israel accused Iran on Wednesday of being behind a deadly attack against Israeli tourists at an airport in Bulgaria, which Sofia said killed seven people and wounded more than 30 others.

There was no immediate confirmation of the nationalities of the casualties, but Israel's foreign ministry said the blast had targeted a bus carrying Israeli tourists who had just landed at the port city of Burgas on the Black Sea.

The United States moved to freeze the assets of dozens of Syrian ministers Wednesday, piling pressure on the regime as it reeled from a bomb attack that took out three core security officials.

The White House insisted President Bashar Assad was "losing control" of power, as Washington marshaled its forces to push the regime toward its tipping point.