BEIRUT — The jihadis of the Islamic State group launched a series of attacks in southern Syria on Wednesday, shattering the quiet that had reigned in the area and killing at least 90 people, according to local officials and a war monitor.

The attacks, which included suicide bombings at a vegetable market and a public square in a provincial capital, along with raids on nearby villages, showed that the Islamic State, also known as ISIS, could still inflict great damage in Syria, despite having lost most of the territory it once controlled.

The high death toll undermines the Syrian government’s narrative that the seven-year war is heading toward its conclusion, with President Bashar Assad working to restore stability. The dead included dozens of pro-government fighters, a conflict monitor said.

The attacks hit the city of Sweida, the capital of the province of the same name, along the border with Jordan. Most of the residents are members of the Druze sect, and the area has largely been spared the violence that has torn apart other areas of Syria during the war.

Four suicide bombers entered the city Wednesday morning, Syrian state television said. One, on a motorcycle, struck a vegetable market. Another detonated his explosives in a public square. Two others blew themselves up while being approached by security forces, the broadcaster said.

At the same time, Islamic State militants attacked villages to the city’s north and east, killing civilians and clashing with local militias, residents said.

“The people in eastern villages woke up this morning to see dead bodies in streets, some of them slaughtered,’’ Mazayiad Hasson, a resident, said through a messaging app.

The Syrian Observatory for Human Rights, a monitoring group in Britain that opposes the Syrian government, put the overall death toll at more than 100, including pro-government fighters, civilians, and militants. The Islamic State claimed responsibility for the attacks on its social media channels.