Former Patriots S Sergio Brown (No. 38, right side of photo) broke Rob Gronkowski's left forearm (No. 87) during a late extra-point attempt Sunday. (CBS screenshot)

Everyone was shocked when news broke that Rob Gronkowski suffered a broken forearm at the end of New England’s 59-24 win over the Colts Sunday night.

Those still watching when the Patriots attempted their final extra point may have seen former New England safety Sergio Brown rush on the inside and crumple Gronkowski’s left arm, but there was little to indicate that a serious injury occurred.

Even Gronkowski’s teammates were shocked to hear the news. The injury is expected to keep him out four to six weeks.

“I knew he had gotten injured, but I obviously didn’t know the extent,” Tom Brady said during his weekly appearance on WEEI’s “Dennis & Callahan” show. “He’s such a great player, it sucks that he gets hurt, but it’s part of this game. He’s got to do his best to get back as soon as possible, and we’ve got to out there and win some games without him.”

Gronkowski, who has 748 receiving yards and 10 touchdowns, had surgery at Mass. General Hospital early Monday morning. 

That means he’ll at least miss games against the Jets, Dolphins, Houston and San Francisco. If he’s on the higher end of the estimate, that puts him back in time for the playoffs. Earning a first-round bye could become hugely important for both Gronkowski and the Patriots under the latter scenario.

New England is hoping to get Aaron Hernandez, who has been sidelined the last three games with an ankle injury, back on the field for Thursday’s game against the Jets. Visanthe Shiancoe, Daniel Fells and Michael Hoomanawanui are next on the depth chart.

None of those players can duplicate what Gronkowski brings to the table as both a receiver and blocker, but the team is already taking a “next man up” philosophy with the injury. The problem is that the coaching staff will not have much time to come up with plan for replacing Gronkowski with New York right around the corner.

“Everyone’s got to get in there and start trying to make up for having Gronk out,” Brady said. “That’s just part of it, and you’ve got to find ways to adjust, and no one really cares. No one cares what’s going on with us.

“We’ve got to go out there and still go out there and win.”

Nick Underhill covers the Patriots for MassLive.com. Follow him on Twitter @CBSPats or @Nick_Underhill.