godan verb (-su), intransitive verb
happen to be present; be there by chance
Describes being at a location when something occurs, often unexpectedly. Similar to 居合わせる, but slightly more literary or old-fashioned.
See also: 居合わせる
その場に居合わせた人たちは皆驚いた。
Everyone who happened to be there was surprised.
偶然、事故の瞬間に居合わせてしまった。
By chance, I happened to be present at the moment of the accident.