BOSTON — An Indian national in the country illegally has been charged with stabbing two teenage boys with a metal fork during a Lufthansa flight from Chicago to Germany, forcing the plane to divert to Boston after a violent mid-air outburst that left passengers terrified.

Federal prosecutors say 28-year-old Praneeth Kumar Usiripalli attacked the victims — both 17 — while the jet was cruising over the Atlantic on Saturday. According to court documents, one boy was lightly sleeping in his seat when he awoke to find Usiripalli standing over him. Moments later, Usiripalli allegedly plunged a metal fork into the teen’s shoulder, then turned to the second boy and stabbed him in the back of the head.

The chaos didn’t stop there. Witnesses told investigators that Usiripalli made a gun gesture with his hand, placed it in his mouth, and pretended to pull the trigger. He then allegedly slapped a nearby female passenger and swung at a flight attendant who tried to intervene.

Pilots of Lufthansa Flight 431 quickly diverted the aircraft to Boston Logan International Airport, where federal agents and state police boarded the plane and arrested Usiripalli on the tarmac. Both teenage victims received medical attention for non-life-threatening injuries.

Prosecutors say Usiripalli had entered the United States years ago on a student visa but no longer has lawful immigration status. He had reportedly been enrolled in a master’s program in biblical studies before his status lapsed.

Usiripalli now faces a federal charge of assault with a dangerous weapon with intent to do bodily harm while traveling on an aircraft, a crime punishable by up to ten years in prison and a $250,000 fine. He remains in federal custody and is expected to appear in U.S. District Court in Boston at a later date.