CORVALLIS, Ore. -- As coach Dennis Erickson said goodbye to his players, Oregon State began its search for a new head coach.

"He left a good foundation here,'' linebacker Richard Seigler said. "I think everybody's hoping we just keep it up.''

Erickson, who built a 31-17 record at Oregon State over a four-year tenure, was announced as the new head coach of the San Francisco 49ers on Tuesday.

Although Erickson's name had been bandied about earlier for the 49ers' job -- as was Oregon coach Mike Bellotti's -- the news that he was leaving came as a shock to many of the players.

"It's still kind of spinning right now,'' quarterback Derek Anderson said. "I'm not sure what to think.''

Replacing Erickson will be the first major challenge faced by Bob De Carolis, named Oregon State's athletic director last August.

In Erickson, De Carolis had a staunch supporter and affable spokesman for the school's plans for an $80-million, 8,000-seat expansion to Reser Stadium.

"It's always hard to leave the players and the boosters and the Beaver Nation because they've been so good,'' Erickson said Tuesday evening in an impromptu news conference. "But I'm at the point in my life right now that this opportunity doesn't come very many times, and I really just had to take advantage of it.''

Erickson, formerly coach of the NFL's Seattle Seahawks, was hired by Oregon State in early 1999 to replace Mike Riley, who left to coach the San Diego Chargers. At the time, Erickson suggested he might want to finish his career in Corvallis.

In his first year, Erickson led Oregon State to a 7-5 record, the team's first winning season since 1970. And he was the first OSU coach to take his team to a bowl game in his first year.

His best season with Oregon State came in 2000, when the Beavers went 11-1 and beat Notre Dame 41-9 in the Fiesta Bowl.

Last season, the Beavers went 8-5, but finished on a disappointing note with a loss to Pittsburgh in the Insight Bowl.

Erickson, Oregon State's 28th head coach, leaves the collegiate coaching ranks with an overall record of 144-57-1 and a .715 winning percentage. His resume includes head coaching stints at Idaho, Washington State and Miami, where he won two national championships.

But that Super Bowl ring always loomed, he said Tuesday.

"To compete for a world championship, I guess, is the itch I had to scratch,'' he said. "That's basically what it boils down to.''

Erickson met Tuesday night with his players before catching a flight to San Francisco, where a news conference was scheduled for Wednesday to formally announce his appointment.

The mood of the brief meeting was somber, players said.

"We're just kind of shocked that it all happened,'' safety Mitch Meeuwsen said. "We're not thinking about what's going to happen.''

Already talk was centered on who the Beavers might choose to replace Erickson. Mike Riley, the Beavers' former coach who is an assistant with the New Orleans Saints, left a message on De Carolis' voicemail, De Carolis said.

Although Riley, a Corvallis native, left the Beavers after just two years for the Chargers, De Carolis said that wouldn't be held against him.

"Mike had an opportunity to be an NFL coach,'' De Carolis said. "If anybody in this room had the opportunity to go to the pinnacle of their career, wouldn't you take that opportunity? I think the answer is yes.''

Current Oregon State offensive coordinator Tim Lappano also expressed interest.

De Carolis said everyone, both inside and outside the program, would be considered. No timetable for a decision was set.

"While we're going to miss Dennis Erickson, we're not going to miss a beat,'' OSU President Tim White vowed. "That's a very important concept to us.''

De Carolis said assistant coaches were calling recent recruits who signed letters of intent last week.

They included quarterback Ryan Gunderson, a Portland-area prospect who was also recruited by Tennessee, and highly touted linebacker Andy Darkins from Lake Oswego High School.

"The timing is never right on anything like this,'' Erickson said about his abrupt departure's impact on the recruits. "Whether it was a week before signing or two months from now or whenever it was, the timing is never right when you leave.''

While the players understood Erickson's decision, that didn't soften the blow, Seigler said after the meeting.

"Coach Erickson was a great coach and he will be missed,'' he said. "No doubt about it.''