COLUMBUS, Ohio — A man crashed his vehicle into pedestrians on the Ohio State campus Monday, then slashed students with a butcher knife before being fatally shot by a university police officer, authorities said.

Nine people were rushed to hospitals and one was in critical condition, according to university police chief Craig Stone. He said it did not immediately appear that the attacker used a gun.

"We are very fortunate that an OSUPD officer was there and took quick action," Stone said.

The drama began shortly before 10 a.m. ET, when the suspect, who was not named, deliberately drove up over the curb and began his attack, he said.

"Buckeye Alert: Active Shooter on campus. Run Hide Fight. Watts Hall. 19th and College" the university's emergency management agency tweeted. "Run hide fight" is emergency protocol used to warn people to flee if possible, hide from the shooter and, if all else fails, fight for your life.

Later, the agency tweeted a warning to "Continue to shelter in place in north campus area. Follow directions of Police on scene."

A SWAT team, K9 and bomb squad units and scores of law enforcement officials descended on the sprawling campus. Less than two hours after the first alert, university police said the shelter-in-place order was lifted and the "scene was secure." Classes were canceled for the rest of the day.

"We prepare for situations like this but we hope we never have one," school President Michael Drake said.

Ohio State's Wexner Medical Center said four patients were being treated there, none with life-threatening injuries. Victims were also taken to OhioHealth Grant Medical Center and OhioHealth Riverside Methodist Hospital.

Peterson Pierre, a junior biochemistry major, said he woke up to the campus alert. He and his roommate decided to go outside and see what was happening.

"We saw a body covered with a white sheet," Pierre said.

Other students hunkered down in their apartments, waiting for the threat to pass.

"It's honestly kind of terrifying because I was at home and away from my phone at the time,” said Jenny Chen, who stayed in her apartment about two blocks from Watts Hall, listed on the school's website as a Materials Science and Engineering building.

“I got flooded with messages ... asking me if I was safe and I didn't even realize this was happening,” said Chen, a senior. “Now I'm just scrambling to make sure that people I know are safe as well.”

Victoria Morishita, a senior studying logistics management student, said she was off campus, but her phone quickly loaded with texts from people near the scene.

"I was scared because it happened near our CBEC and business building and a lot of my friends were there," she said.

Twitter filled with well-wishes from federal, state and local officials.

".@TeamTrump watching coverage of what has transpired @ Ohio State - Thoughts & prayers are with the students & administration at this time," tweeted Dan Scavino, social media director for President-elect Donald Trump.

"Ohio's thoughts and prayers go out to the Ohio State community," Gov. John Kasich tweeted. "Be safe, listen to first responders."

Tweeted Rep. Tim Ryan, D-Ohio: "Everyone stay safe — Monitoring this situation closely. Thoughts and prayers with everyone on campus."

"We are all Buckeyes. Our thoughts are with all of @OhioState and Columbus today," tweeted the Cleveland Cavaliers basketball team.

Ohio State’s 1,764-acre campus is located about 2.5 miles north of Columbus. The school, founded in 1870, is the third-largest campus in the U.S. with about 45,000 undergraduates and 13,000 post-graduates.

Contributing: Walbert, Castillo; The Enquirer in Cincinnati