At least 13 people were shot at a bar in Thousand Oaks, California, late last night. Here’s what we know so far:

At least 12 people were killed. A gunman walked into Borderline Bar and Grill in Thousand Oaks at around 11:20 p.m. and opened fire, killing at least 11 patrons and a responding officer and wounding at least one other before taking his own life. The Ventura County Sheriff’s Office said 18 people transported themselves to local hospitals, and two others were transported by ambulance, most with minor injuries.

The bar was hosting a “college country night.” Wednesdays are “college country night” at Borderline, a large country and western venue with popular line dancing classes. Patrons frequently include students from California Lutheran University, California State University/Channel Islands, Pepperdine University, and Moorpark College, all of which are a relatively short drive away. One group of young people was there to celebrate a friend’s 21st birthday.

More patrons were injured trying to escape. Many escaped by throwing chairs through windows and then climbing out to safety. Anguished relatives, friends, and roommates spent the early morning hours seeking contact with loved ones yet to be heard from.

The gunman was carrying a Glock .45 pistol with an extended magazine, Ventura County Sheriff Geoff Dean said. He’s been identified as Ian David Long, 28, a Marine Corps veteran who was on active duty from August 2008 to March 2013. Dean said police had responded to a disturbance at Long’s home earlier this year, but that Long did not qualify for an emergency psychiatric hold. One of Long’s neighbors in the nearby town of Newbury Park told ABC 7 that Long suffered from PTSD, adding, “I don’t know what he was doing with a gun.” According to the The Los Angeles Times, Long drove his mother’s car to the bar.

The officer who died has been identified. Sergeant Ron Helus was a 29-year veteran of the Ventura County Sheriff’s Office who was planning to retire next year. “As I told his wife, he died a hero, because he went in to save other people,” Sheriff Dean said, choking back tears at a pre-dawn news conference.

Thousand Oaks frequently ranks as one of the safest cities in the country. Before last night, the city of 130,000 northwest of Los Angeles had just five shootings during the past five years, according to Gun Violence Archive, resulting in a total of four deaths and two injuries.

At least one witness lived through the Las Vegas massacre, according to her friend, who rushed to the scene. “There’s people that live a whole lifetime without seeing this, and then there’s people that have seen it twice,” he said.

The local sources we’re following include @latimes, @vcstar, and @VENTURASHERIFF. We’re also sharing updates as they come in from our own Twitter feed, @teamtrace.

The Borderline Bar and Grill rampage was the 307th mass shooting in 2018, according to Gun Violence Archive. Here’s our guide to understanding this deadly phenomenon.