Four men were killed in Howard County early yesterday when a pickup truck carrying two of them swerved into oncoming traffic and collided with the pickup truck in which the other two were riding, police said.

The crash, on Interstate 70 in western Howard, snarled traffic on the highway for more than five hours after police closed all three westbound lanes while they investigated.

According to police, Jose M. Sanchez, 27, of New Market, was driving east on I-70 near Route 97 in Cooksville about 6:40 a.m. with Marco A. Gonzalez, 23, of Frederick. They were in a white Chevrolet pickup belonging to their employer, Ben Lewis Plumbing in Clarksburg.

The truck swerved suddenly, crossed the grass median strip and struck the driver's side door of a maroon Chevrolet pickup, which was traveling west in the middle lane and carrying two men from Baltimore County, police said. All four died at the scene.

Police identified the driver of the maroon truck as Charles R. Wilhelm Jr., 66, of Monkton, Md., and his passenger as James Gillispie, 75, of Parkton, Md. The two were longtime friends headed for a NASCAR race taking place today in Martinsville, Va., said Tom Ruhl, Wilhelm's son-in-law.

Cpl. D. Vinson said police are trying to determine why the white truck crossed the median, although he said that neither alcohol nor drugs were a factor in the crash. Weather also did not appear to be a cause, police said. They said Wilhelm appeared to be the only one wearing a seat belt.

Hours after the accident, pieces of rubber from a blown-out tire remained at the scene. The trucks "were totally destroyed," Vinson said. "You couldn't tell which was which."

The front of the white truck was smashed in, its engine exposed. The driver's side door of the other had been ripped off and its hood crumpled.

Ruhl said that Wilhelm, a retired insurance adjuster, and Gillispie had been best friends for more than 50 years. They lived about 10 minutes from one another and often rode in Wilhelm's car to grab breakfast or a cup of coffee, he said.

The men loved NASCAR races, said Ruhl, who lives in a house about 100 feet from his father-in-law. The three of them attended the Daytona 500 together in February, Ruhl said. He said Wilhelm and Gillispie were friends with the vice president of the Martinsville Speedway and had planned to spend the day with him and then drive back after the Kroger 200 truck race today.

"Those two probably had a million miles together going to the races," Ruhl said. "That's when they were at their best, when they were together driving."

A woman who answered the phone at Gillispie's home declined to comment. The families of Sanchez and Gonzalez could not be reached, and representatives of Ben Lewis Plumbing did not want to comment.