An 18-year-old Brooksville man who police say struck and critically injured a woman walking along a road in Hernando County an hour earlier apparently shot and killed himself late Thursday in Levy County after police stopped him for speeding.

Police in Levy County report that they stopped Andrew Altringer (left) after he was clocked doing 80 mph in a 45 mph speed zone on U.S. 19 in Inglis at 11:07 p.m. Deputies pulled in behind Altringer's vehicle with their overhead lights and siren on, and he slowed to 65 mph before pulling onto a median along the highway about a mile north of the Inglis city limits, according to Capt. Evan Sullivan of the Levy County Sheriff's Office.

As officers approached Altringer's 2008 Mazda, Sullivan said, they heard a loud gunshot from inside the vehicle and saw that Altringer had apparently shot himself with a rifle. He was taken to Seven Rivers Regional Medical Center in Crystal River, where he was pronounced dead.

According to the Florida Highway Patrol, about an hour earlier, Altringer had been driving east on Meinert Avenue south of Hexam Road in northwest Hernando County when his vehicle went off the road and struck Alicia Anderson, 22, of Lynn, Mass. from behind as she walked along the road. Altringer did not stop or call for help, the FHP said, but sped off.

Reports indicate that Kyle Case, 17, of Brooksville was a passenger in Altringer's car at the time of the accident but not when Altringer was stopped in Levy County.

Anderson was taken to Oak Hill Hospital in Spring Hill then transported to Tampa General Hospital, where she was reportedly in critical condition Friday morning.

Altringer was a senior at Central High School in Brooksville, where officials said he was an honors student and a member of the school's JROTC chapter.

Altringer also was a member of the National Guard Military Police 690th Unit based at the Crystal River National Guard Armory. A spokesman for the National Guard said Friday that Altringer went through basic training last summer and was scheduled to attend specialized military police training this summer. The unit is scheduled to be deployed to Afghanistan in 2010, and Altringer presumably would have gone with them.

The spokesman, Jon Myatt, of the Florida Department of Military Affairs, said the unit commander was notified immediately after the incident and that word was passed throughout the unit. "This is a sad event for us, his National Guard family,'' Myatt said. Myatt said that the weapon Altringer used to kill himself was not military issue. He noted that weapons are only issued during operations and that they are returned at the end of the exercise.