Security forces, emergency services and residents examine the remains of burned vehicles at the site of a bombing in Tartus, Syria. (Syrian Arab News Agency via AP)

A string of explosions across Syria, most of them targeting government checkpoints, killed at least 40 people on Monday as talks between the United States and Russia on a cease-fire in the war failed.

The deadliest attack was a twin bombing on the loyalist province of Tartus, according to the official Syrian Arab News Agency. A car bomb first exploded on a bridge, and then a suicide bomber struck when people gathered to take the wounded to a hospital, SANA said. At least 30 people were reported killed.

Elsewhere, four people died in an explosion at a checkpoint in the city of Homs, and one person died in a bombing in the countryside surrounding Damascus, the capital. Five people died in a motorcycle bombing in the northeastern city of Hasakah.

The Islamic State militant group asserted responsibility for the bombings, as well as one that targeted Syrian Kurds in the northeastern city of Qamishli and was not reported by SANA.

At least 60 people were injured in the blasts.

Bombings are commonplace in Syria, and airstrikes kill similar numbers on a daily basis. But attacks like the one in the loyalist stronghold of Tartus, a coastal province mostly populated by the Alawite sect to which President Bashar al-Assad belongs, are relatively rare. The province is home to Russia’s main naval base in Syria.

The attacks suggest that the cycle of violence in Syria is unlikely to end anytime soon, especially in the wake of the failed U.S.-Russia cease-fire talks.

U.S. officials had hoped to reach a deal in time for President Obama’s meeting on Monday with Russian President Vladimir Putin on the sidelines of the Group of 20 summit in China. The meeting went ahead with no agreement in sight, although the two sides said they would continue to talk.

The agreement was to have focused on the northern city of Aleppo and ways to deliver humanitarian aid to needy civilians. The effort was complicated Sunday by fresh gains by government forces that entirely cut off the rebel-controlled portion of the city, leaving an estimated 300,000 civilians without access to the outside world.

Zakaria reported from Istanbul.