Superintendent Richard Moore of Birmingham Central Police said the fatal stabbing of two men in Birmingham city centre was a "dreadful" and "exceptionally rare" incident.
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The paralympian posted a time of two minutes and 57 seconds on Sunday.
The 17-year-old posted a supportive Instagram message accompanied by a childhood photo.
"Big Sam" was spotted letting his hair down in the seaside resort weeks after securing Premier League survival for Sunderland.