All precincts reporting:
Tsongas 54,363 (51%)
Ogonowski 47,770 (45%)
Murphy 2,170 (2%)
Hayes 1,125 (1%)
Thompson 494 (0%)
UPDATE: Town-by-town results are here (thanks johnk).
Hold onto your hats. I'll update as I hear more. Tsongas is the winner. Congratulations to her and her hardworking campaign staff! UPDATE: I'm hearing that WBZ has called it for Tsongas.
Further UPDATE by Charley: Lynne is telling me 53-47 will likely be the final result, once all precincts are in. Matt Murphy of the Lowell Sun says it's over. Niki declares victory.
Another UPDATE: Ogonowski's not conceding. Funny.