PHOENIX -- The trade that sent LeSean McCoy from the Philadelphia Eagles to the Buffalo Bills earlier this month took just 30 minutes to complete after the Bills were "stunned" to learn McCoy was available, coach Rex Ryan said Tuesday.

The Eagles called the Bills about LeSean McCoy being on the trade market, Buffalo coach Rex Ryan said, and it took very little time for the teams to hash out a deal. Kevin Hoffman/USA TODAY Sports

"The trade for LeSean happened really quick," Ryan said at the NFL owners meetings. "We were all sitting there. We were having organizational meetings. ... And all of the sudden we get this call from Philadelphia and I think that was when the trade started. Probably 30 minutes later, the trade was done."

The March 4 deal sent McCoy, the NFL's third-leading rusher since he entered the league in 2009, to Buffalo in exchange for linebacker Kiko Alonso, who missed last season with a torn ACL.

The Eagles called the Bills about McCoy being on the market, which surprised the Bills.

"We were just kind of, like, stunned there for a little bit," Ryan said. "We're like, 'Really? Wow.' All right, so let's just take it from there. Obviously we were interested and then the trade came down. We knew it wasn't going to be cheap by any stretch. And losing a player like Kiko Alonso is obviously a steep price, but we felt really good about it."

McCoy will become the "bell cow" in the Bills' backfield, Ryan said Tuesday, but the Bills did not enter the offseason expecting to add a top-tier running back like a three-time Pro Bowler in McCoy.

"We never saw it. It was an opportunity. I think that's it," Ryan said. "We're not just so structured that you can't just allow something like this to happen. Clearly it was an opportunity for us. We all talked about it and it didn't take us long to come up with the conclusion we did, which was let's go ahead and get him."