Police are going door to door at Yale University to search for a gunman on campus, a spokesman has warned.
Yale University urged students and staff to co-operate, warning, "When they knock on your door, a Yale police officer will slip their Yale ID under the door".
"Police may use keys, but they will identify themselves", the university website added.
Libraries and some public schools are also on lockdown as the search continues, New Haven Police Department spokesman David Hartman said.
More top news
Clocks will go forward 30 minutes so there is half an hour more daylight in the evening when energy consumption peaks.
The Boeing 777 was reportedly intercepted by two Hungarian Air Force Gripens after it lost contact with air traffic controllers.