Police and school officials said four people were wounded, one critically, in a shooting that erupted at a San Francisco high school parking lot after school had been let out for the day. The San Francisco Unified School District said in a statement that a fourth person was also wounded but could not provide any further information on the victim. The school was placed on lockdown, which has since been lifted. The latest school shooting reveals rising gun violence in the United States.

The incident was the latest in a series of mass shootings at U.S. schools that has fueled debate about gun violence. A South Carolina teenager killed his father and opened fire at an elementary school in late September, wounding two students and a teacher. There have been as least 196 school shootings in the U.S., an average of nearly one in a week, according to a report released by Every Town for gun safety. The report also states that the South Carolina shooting is the 37th school shooting of 2016 and the sixth since the start of fall term.