Texas election officials have uncovered over 10,000 uncounted mail-in ballots in Texas’ most populous county over the weekend.

According to reports by The Washington Examiner:

Two close Democratic primary races, one for a state House seat and another for Texas attorney general, hang in the balance. The ballots, 6,000 for Democrats and 4,000 for Republicans, were scanned into the tabulation computer, but they were not added to the unofficial final results, Harris County officials announced Sunday.

“While we understand the seriousness of this error, the ability to identify and correct this issue is a result of a lengthy and rigorous process and is a positive example of the process ultimately working as it should,” the county, which includes most of Houston, said in a statement obtained by the Texas Tribune.

Candis Houston, who is trailing incumbent state Rep. Harold Dutton Jr. by 136 votes in the Democratic primary, has already conceded the race. Dutton was baffled that so many ballots had gone missing without anyone noticing.

“It seems to me that somebody should’ve known that 10,000 ballots were missing,” Dutton said. “If 10,000 ballots were missing and nobody knew that, God help us.”

Harris County faced a number of complications reported for the March 1 primary. Delays caused by 1,600 damaged ballot sheets, two voting locations reporting minor technical difficulties with their machines, and a shortage of election workers all added to the already stressful primary season.