A Littleton tractor-trailer driver critically injured Thursday evening when he was hit by a rock thrown by a person on Interstate 95 in Milford, Conn., was still listed in good condition Tuesday afternoon.

Wayne Tapley, 48, was northbound in his tractor-trailer at about 8:30 p.m. Thursday when he was struck by a rock that came through his windshield, police said.

Tapley may have been dazed or knocked unconscious by the rock, causing him to lose control of the vehicle and sideswipe a bus. The tractor-trailer then careened off the median barrier, swerved back across the highway and plunged down a steep embankment.

Tapley had to be extricated from the vehicle and was taken by ambulance to Yale New Haven Hospital. His condition is steadily improving since the accident, according to his daughter, Jenna Tapley, who is with him.

“My dad is doing much better,” Tapley said. “His vital signs are strong, and his nurses are making him walk and exercise a little. It’s a very good sign.”

Tapley and her mother, Nicole Tapley, were informed of the accident after police officers found the registration to the tractor-trailer that Tapley was driving. Police notified James Westerdahl of Littleton, the owner of the vehicle, who then informed the family. Tapley was hauling a load of tomatoes at the time of the accident.

Tapley underwent surgery Thursday night to repair facial injuries he incurred in the accident, his daughter said.

“My father had to have a lot of facial surgery,” Jenna Tapley said. “He had surgery on his forehead, on the bones under his eye and on his eyebrow, and on around the bridge of his nose. He was unconscious for two days due to the anesthesia. He is awake now, but he is still very groggy.”

Police say that they have several leads in the case but have made no arrests.

“We have more information in the criminal investigation that will hopefully lead us to the next level,” Sgt. J. Paul Vance, spokesman for the Connecticut Department of Public Safety, said Tuesday. “We still do not know if it was one person or many that threw the rock, but it doesn’t matter whether this type of crime is done in Connecticut or Maine … it is always a recipe for disaster.”

Police concluded that Tapley drove a quarter-mile after he was hit by the rock. This adds to the severity of the situation, Vance said.

“We don’t know if he passed out and his foot stayed on the accelerator or what,” Vance said. “We have had cases before where rocks were thrown at vehicles, and it has mostly been tied to juveniles. No matter who did this, this is a major crime, and a lot of lives could have been lost in this accident.”

Though hospital officials are unsure when Tapley will be released, his daughter said, “He will have to do some rehabilitation in Bangor, but at least we will be much closer to home. Everyone here at the hospital and at home are really supportive, and it is really affecting us,” she said.

“My dad is fighting to go home right now.”