Days before its scheduled launch date, most of the city’s new light rail system was shut down to trains on Wednesday.

For much of the day, trains were not running on most of the LRT line, from Lees Station east of the downtown tunnel to Tunney’s Pasture Station at the western end of the line.

In a statement Wednesday afternoon, the city said three radio units that are a part of the control system needed to be reset.

Three trains stopped in the tunnel, said the statement, attributed to Director of Transit Operations Troy Charter.

Two of the trains were taken to Tunney's Pasture and one returned to operations in the east end. The problem was resolved by 2 p.m.

The disruption comes less than two weeks ahead of LRT’s Sept. 14 launch date. It also comes one day after the city said the Rideau Transit Group had achieved ‘revenue service availability,’ marking the official handover of the system to the city. That handover came more than 15 months after the originally scheduled date of May 24, 2018.

OC Transpo general manager John Manconi told CTV News that the problem started around 4:30 a.m. Officials are investigating the possibility that the radios -- essentially the GPS of the system that shows exactly where the trains are -- could have been knocked out by lightning in a massive thunderstorm around 3 a.m.

Manconi said the system worked as it was designed to do. The radios were rebooted and the service was stopped until 2 p.m. for an 'operations sweep' to investigate the radio control system.

There was no damage to any infrastructure, he said. If this had happened with passengers on board, all the trains would have simply been moved to the next station and passengers wouldn't have been stranded.

Manconi also said the planned launch date of Sept. 14 hasn't changed.

The $2.1-billion line will serve 13 stations from Tunney’s Pasture in the west to Blair Station in the east.