"He's got a little MCL sprain in his other knee, and so we have just got to see what that means," Carroll said. "He went back in the game and played some, but we just eventually kind of talked him out of playing because he wanted to keep going. And we just want to make sure we take care of him."
Carroll did not know how long Baldwin will be out.
Baldwin injured his right knee, which is not the same knee that was previously injured.
Baldwin went down in the first quarter and started limping off the field before he went down again and had to be tended to by the team's medical staff. He eventually walked off on his own power and returned later in the first half.
A press-box announcement early in the third quarter indicated that he would not return to the game.
Baldwin was held without a catch on one target, and Seattle went into halftime trailing 17-10.
"Doug is a true playmaker. He's done it for years. I know he's going to do everything he can to get back as soon as possible," quarterback Russell Wilson said after the game.
Baldwin, who has led Seattle in receiving in five of his seven NFL seasons, missed about a month of training camp with a left-knee injury. He estimated when he returned to practice in late August that he was 80 to 85 percent healthy and said his knee injury was something he would have to deal with throughout the season.
Brandon Marshall is among the receivers who would stand to play more if Baldwin's injury forces him to miss time. Marshall caught three passes for 46 yards and a touchdown Sunday.
In other injury news, Carroll said strong safety Bradley McDougald was dealing with a knee injury -- specifically mentioning his patellar tendon -- that forced him out for a few plays. McDougald had two of Seattle's three interceptions.