DAMASCUS, Sept. 5 (Xinhua) — Several bombings rocked key Syrian cities almost simultaneously Monday, killing at least 48 people, as Russia and the United States fail short of concluding negotiations on a cease-fire in Syria.

The first bombing happened in the central city of Homs at 7.14 a.m. local time (0414 GMT), when a booby-trapped car was detonated after being discovered by government soldiers at a checkpoint at the Bab Tadmur area.

Four people were killed and many others wounded in the explosion.

Had it not been stopped, the vehicle could have caused much heavier casualties if the powerful explosives detonate inside the city, the national Syrian TV said.

The Homs blast also left property damage in an area almost deserted form civilians in that part of the city.

It said the explosion came as authorities and rebels in al-Waer were working to establish reconciliation that might lead to an end to insurgency in the neighborhood, the last rebel-held district inside the city of Homs.

In the coastal city of Tartus, at least 35 people were killed and dozens of others wounded on Monday, in twin bombings that rocked a checkpoint at the city's entrance, said the report.

An explosive-laden vehicle was detonated at the checkpoint of the entrance of Tartus, when it was discovered by military personnel, said the report.

Another explosion followed when a suicide bomber detonated his explosive belt among a crowd who gathered to help the wounded in the first blast in Tartus, said the report.

The suicide car bomber had apparently planned to detonate inside the city but did so at the entrance after he was discovered by the authorities, the report said.

Both bombers, wearing military uniforms, were disguised as members of government troops, the military said.

It wasn't the first time Tartus, once one of the safest cities in Syria, was targeted by explosions.

On May 23, eight bombings were carried out by the Islamic State (IS) militants in the cities of Tartus and Jableh, another coastal city, killing 184 people and wounding at least 200 others.

Also on Monday, an explosive-packed motorcycle ripped through a checkpoint for the Kurdish Assayish security forces in the predominantly-Kurdish city of Hasakah in northeastern Syria, killing eight people.

In the capital Damascus, an explosion rocked a road between the summer resort town of Sabura, and Bajaj, killing one man.