Two men died taking part in the Great North Run, race organisers have said.
The two men, both aged 25, collapsed during Sunday's event, which involved 63,000 runners.
Both men, who were from the North East, were competing in the 13.1-mile route, the Great Run Company said.
The event organisers said the two runners died despite the "very best efforts" of medical teams.
The cause of death has yet to be determined.
The organisers said no further details will be released out of respect for the men's families.
The Great Run Company said: "Everyone involved in organising the Great North Run extends their heartfelt condolences to the family and friends of the two participants.
"We are continuing to support their families during this incredibly difficult time, and our thoughts and sympathies are with all those who loved and knew them."
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The event, which is the world's biggest half marathon, was the 45th staging of the Newcastle to South Shields run.
Andy Burnham became the first sitting prime minister to take part in the run.
He signed up at the start of this year while still in office as mayor of Greater Manchester - and raised money for Changing Lives, which he visited last month to launch a national drive to end rough sleeping.
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