At least 31 people were killed and 90 were injured on Thursday morning during an attack in an open-air market in Xinjiang province in western China.

According to the Associated Press, China’s state-run Xinhua News Agency reported that two automobiles drove through crowds and the assailants began throwing explosives out the window. The vehicles then crashed and one exploded, setting off more blasts.

"I heard four or five explosions. I was very scared. I saw three or four people lying on the ground," Fang Shaoying, the owner of a small supermarket said.

CNN noted that this is the latest attack to hit the country in recent months. Last month, an explosion at a train station killed three people and injured 79 others. And in March, a knife attack at another train station left 29 people dead.

It is not yet known who was responsible for Thursday’s attack, however, the recent violent incidents have been blamed on separatists looking to overthrow the government.

Most of those killed were people who shopped at the marketplace regularly during the morning hours.