Donald Trump's campaign has filed a lawsuit in state court accusing Clark County, Nevada, of keeping the polls open beyond closing time Friday, the final night of early voting.

Both Trump and Nevada GOP chairman Michael McDonald complained Friday night that a polling location in a Hispanic neighborhood in Las Vegas was kept open improperly. Trump called it evidence of a "rigged system."

Dan Kulin, a spokesman for Clark County, told NBC News on Sunday that nothing improper happened. Under Nevada law, voters may vote as long as they were in line at the time that the poll was scheduled to close. (This is standard in most, if not all, states.)

At 7 p.m. PT, the scheduled closing time, there was still a long line, Kulin said. He said the last vote at the site was cast shortly before 10 p.m. PT.

"Nothing happened that wasn't supposed to happen," Kulin said. "Voters who were in line by the scheduled closing time were allowed to vote."

The Trump campaign claims otherwise: that voters who were not in line at 7 p.m. were allowed to vote.

A hearing is scheduled for 11 a.m. local time Tuesday.