DAMASCUS, Syria — Syria's transport ministry said a freight train carrying phosphate derailed and caught fire Sunday after getting hit by explosives planted on the tracks by militants in the country's center.

The government-owned train was transporting phosphate from mines in Khunayfis in Homs province, and the ministry said technical teams were working to repair the railway and restore traffic.

Last week, militants also targeted a gas pipeline in Homs province.

A Russian company controlled by a childhood friend of President Vladimir Putin has secured a 50-year concession from the Syrian government for most of the output of the major phosphate field in Homs after the mines were liberated from the Islamic State group in 2017. The same company has an agreement with the Syrian government to rebuild the country's only fertilizer plant and develop one of its main ports.

Russia is a main backer of President Bashar Assad's forces in the country's civil war, now in its ninth year.

Before the war, Syria was one of the world's top exporters of phosphate. IS militants held territory in central Homs and gained control of the phosphate mines in 2015.

Despite the territorial defeat, IS militants remain holed up in parts of central Syria, where they have increased their attacks against government troops. While the government now controls over 60 percent of Syria, there is still a rebel stronghold in the northwest, where the government is waging a limited but stalled offensive. Smaller armed groups in northern, central and eastern Syria have vowed to target government and Kurdish-controlled facilities.

In northwestern Syria, where the nearly four-month offensive continues, first responders and activists said government bombing of the last major rebel area killed at least 11 civilians on Sunday.

The Britain-based Syrian Observatory for Human Rights said six people were killed, including a child, in the government bombing of the village of Urum al-Joz in southern Idlib province. The opposition-operated Shaam news agency said those killed had previously been displaced from the southern tip of the rebel stronghold.

Rescue workers, known as Syria's Civil Defense or White Helmets, said three children and a woman were killed in Kfaruma, south of Urum al-Joz. A White Helmet volunteer was killed in the town of Khan Sheikhoun, the group said.

The offensive began in late April, displacing more than 300,000 people.