Jacob Chesire wins Belfast marathon in record time
Jacob Chesire from Kenya has won this year's marathon in a record-breaking time of two hours 14 minutes and 56 seconds.
The previous record was two hours 15 minutes and 51 seconds by Marty Deane in 1985.
Up to 21,000 people are taking part in events connected to the 30th Belfast Marathon.
Race director David Seaton said the event was "very good" for Belfast with the biggest number of entrants ever.
"We have 21,000 people of all shapes, sizes and athletic abilities," he said.
"It is the biggest entry we have ever had over the years. We, as organisers, are delighted."
Mr Seaton said the conditions were perhaps a little warm for those running the full marathon.
"It will be okay for the fun runners and, maybe, the relay runners. But for some of the marathon runners, out for three or three and a half hours, it could be pretty awkward."
Mr Seaton is running in a relay team made up of five people who competed in the first marathon.
Traffic disruption is expected on a number of routes across the city.
The event began at the City Hall at 0900 BST and finishes at Ormeau Park.
Organisers have said the majority of roads will remain open throughout the event.
Roads affected include Victoria Street, Albertbridge Road, Holywood Road and Sydenham Bypass.
Bridge End, Hillview Road, Gideon's Green and Corporation Street will be closed until 1400 BST.
Ormeau Embankment will be closed from 0700 BST until after 1800 BST.