WATCH: Wheelchair division of the OKC Memorial Marathon underway

The Oklahoma City Memorial Marathon officially began Sunday morning with the start of the wheelchair division, as athletes launched from the line ahead of the main contingent of runners.

Organizers say that this is the largest marathon yet, with around 25,000 runners participating. Runners from all 50 states and 18 countries will join the races.

Wheelchair racers were the first to set off on the 26.2-mile course, rolling past the Survivor Tree and into downtown streets lined with cheering spectators.

Their journey honors the 168 lives lost in the 1995 bombing of the Alfred P. Murrah Federal Building.

Stay with News 9 for live updates, race highlights, and results throughout Marathon Sunday.

OKC Marathon: LIVE UPDATES from Oklahoma City’s 25th Memorial Marathon

Oklahoma City Memorial Marathon: Race weekend guide 2025

Road closures planned in Oklahoma City for Memorial Marathon weekend

'More than a race:' Oklahoma City Memorial Marathon unites community in purpose and motion