ORCHARD PARK, N.Y. -- Buffalo Bills reserve tight end Kevin Everett had surgery on Sunday after injuring his spine against the Denver Broncos, and there is concern about whether he will be able to walk again.

"He's had some sparse movement," Everett's agent Brian Overstreet told The Associated Press in a phone interview late Sunday.

"The next couple of days is going to be critical," said Overstreet, responding to a question about paralysis. "Our concern is for him to come out of this healthy and, hopefully, be able to walk again."

Overstreet said Everett came out of a "lengthy surgery" Sunday evening and the plan was for his mother, Patricia Dugas, to arrive from Texas on Monday.

Everett fell to the ground and never moved after a helmet-to-chest hit when he tackled Denver's Domenik Hixon during a kickoff to open the second half. Everett was placed on a backboard with his head and body immobilized, and carefully loaded into an ambulance at the Broncos 30.

The game was delayed for about 15 minutes, and the Bills gathered at the sideline while doctors attended to the player.

At 9:45 p.m., as he was leaving Millard Fillmore Gates Hospital, Bills' tight end Ryan Neufeld told Buffalo's WIVB-TV the surgery "went well as far as we can tell and he's recovering right now."

Bills general manager Marv Levy said doctors informed the team that it's too early to determine the severity of the injury and they will know more after monitoring the player overnight.

"Certainly, we feel the injury is serious, but I don't want to speculate, and that's what the doctors told us," Levy told The Associated Press. "They told us to wait to hear from them before making any speculative announcement."

Coach Dick Jauron said immediately following the game that the player sustained a cervical spine injury, but wouldn't discuss the severity of the injury.

Everett's injury cast a pall over the Bills following a season-opening 15-14 loss, with several players expressing concern about their teammate.

"It was real hard," cornerback Terrence McGee said. "I watched the whole thing and he never moved. ... It's real sad to see him go off on a stretcher, but we hope he's OK."

"It's real sad," added receiver Roscoe Parrish, who played with Everett at the University of Miami. "When something like that happens to a close friend of yours, and you know how much he loves football, it bothers you."

Denver players expressed concern, including kicker Jason Elam, who kicked the winning field goal as time ran out.

Before taking questions after the game, Elam said: "What we heard is not good, so for our whole team, our prayers go out to him."

Buffalo's third-round draft pick in 2005, Everett missed his entire rookie season with a knee injury, and spent most of his second season limited to special teams duty.

The Bills liked Everett's 6-foot-4 frame, and were counting on him to play a role in their passing attack this season.

Buffalo also lost defensive starters Ko Simpson, Cory Wire and Jason Webster to injuries.

Copyright 2007 by The Associated Press.