Metro's Red Line was experiencing significant delays Wednesday morning after crews discovered a crack in the system's electrified third rail.

Metro officials became aware of the cracked rail between the NoMa-Gallaudet and Rhode Island Avenue stations at about 6 a.m., just as the morning rush was starting. Trains were single-tracking between the NoMa and Fort Totten stations until about 7:50 a.m., Metro spokesman Philip Stewart said.

Most Red Line commuters experienced delays of about 20 minutes while the trains were single tracking. Residual delays lasted until about 8:30 a.m. after the repairs were made, frustrating thousands of commuters.

"I think it's kind of crazy during rush hour time," said Dani Guzman, who was left waiting for a train to take her from Union Station to Tenleytown.

Stewart said that the cause of the cracked rail is under investigation. He was unsure if the rail had cracked after Metrorail service began for the day.