Juan Diasgranados of WPTV is reporting that authorities have said the suspected gunman on MIT's campus stole an officer's gun and shot the officer at MIT. Police are currently looking for a suspect with a cowboy hat.
It should be noted that such immediate reports should be taken with a grain of salt, especially in light of the numerous reporting failures that marred the coverage of Monday's Boston Marathon bombing. Admittedly, the best we can do at this point is tell you what is being reported.
Photo from the scene: