Professional sports intersected with anxiety over school shootings Friday, as a former NFL player caused his old high school to close with an Instagram post. Jonathan Martin, who played three seasons in the NFL as an offensive lineman, was taken into custody for an ominous post to his private Instagram account, Matt Stone of ABC News reported. Harvard-Westlake prep school closed its campuses Friday afternoon in response to the post.

Stone also tweeted a screenshot of the image Martin posted in his Instagram story.

The image depicts a shotgun, surrounded by shells, lying flat on what appears to be a bed or other raised surface. In the upper right corner, Martin tagged four users, including former Miami Dolphins teammates Mike Pouncey and Richie Incognito. On the gun, Martin wrote “#MiamiDolphins” and “#HarvardWestlake.” Finally, to the left of the gun, Martin wrote “When you’re a bully victim & a coward, your options are suicide, or revenge.”

Harvard-Westlake released the following statement, per KTLA-5.

“Last evening, we learned of an Internet post that mentions Harvard-Westlake by name. Out of an abundance of caution, and because the safety of our students, faculty, and staff is our top priority, we made the decision to close school today. We are working closely with law enforcement and will share more information when we are able.”

Martin’s post was the latest of several online posts that temporarily shut down schools in the wake of the Valentine’s Day mass shooting at Marjory Stoneman Douglas High School in Florida. However, none of the previous incidents involved anyone as well-known as Martin, a former second round pick who was involved in a high-profile bullying scandal at the hands of Incognito and Pouncey when the three played for the Dolphins.

When it became clear that Martin needed a change of scenery, the Dolphins traded him to the San Francisco 49ers. He played there for one season before being cut. He was claimed on waivers by the Carolina Panthers in the 2015 offseason, but retired from football before he ever played for them. Martin wrote a lengthy Facebook post after retiring where he admitted he once attempted suicide during his football career and suffered from debilitating anxiety.

GettyImages-107175689 Jonathan Martin #55 and Richard Sherman #9 of the Stanford Cardinal celebrate after they beat the Oregon State Beavers at Stanford Stadium on November 27, 2010 in Palo Alto, California. Photo: Ezra Shaw/Getty Images