From the official site:

General Manager Dale Tallon announced today that Blackhawks center Jonathan Toews is returning to Chicago to have an MRI performed on his left knee. Toews sprained his knee in Tuesday night’s game in Los Angeles against the Kings.

Tallon also announced that the Blackhawks have recalled RW Kris Versteeg from the Rockford IceHogs of the AHL.

I have that sinking feeling that they are going to find another problem with his knee that will cause him to miss somewhere between 4-6 weeks, because that has just been the Hawks' luck lately. I just don't think this team can stay afloat without a guy like Toews, when you consider the fact that they are already reeling from the losses of Havlat, Sopel, Wisniewski, etc.

UPDATE: From CBC Sports:

Jonathan Toews has averaged nearly a point a game for the Chicago Blackhawks this season, but he won't be striking fear into any opponent for perhaps the next month.

The rookie centre suffered a knee injury in the first period of Tuesday's 9-2 rout at the hands of the hometown Los Angeles Kings.

Toews, 19, might have sustained a second-degree strain of the medial collateral ligament and could miss two to four weeks of action, according to Chicago coach Denis Savard.

"I was chasing the puck around in a couple of different directions and I think I just tried to change directions too quick and my leg kind of gave in a little bit," Toews told the Chicago Tribune.

Great. Even though 2-4 weeks isn't terrible and isn't the worst-case scenario, I don't think this team will be staying within the playoff race much longer at this point. There are too many key players injured, and Toews has been probably the best offensive force outside of maybe Patrick Sharp, and has become a leader on this team. He will likely become the 8th player on the Hawks to go on injured reserve, which is just ridiculously bad luck.