Students from Durham University have joined a river-side search for missing Luke Pearce, 19.
He has not been seen since a night out with friends in the city on Saturday night.
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Hundreds have left the Civic Centre in Sunderland as this year's Sunderland Pride gets underway.
It happened after yesterday's football game, which saw Barrow win 2-0 against York City.
All of the fires were extinguished but police are appealing for information. They believe they may have been started 'maliciously'.