What is a hero? The Portland Police define the word for us. Read the department's moving tribute to Detective Benjamin Campbell, as posted on its Facebook page. Campbell was killed on I-95 in Hampden, Maine when he was hit by a truck wheel in a freak accident last Wednesday, April 3rd, according to the Portland Press Herald.

The last line of the tribute reads: "Rest in peace hero. We here in Portland will be eternally grateful for your courage and sacrifice."

There is a memorial service for Detective Campbell at the Cross Insurance Arena in downtown Portland on Tuesday, April 9th at 11 a.m.