MONTREAL -- Flooding that blocked Highway 20 in both directions Tuesday night was the result of insufficient pumping and incomplete water retention ponds, according to Transports Quebec.

A barrage of rain fell on the highway between 4 and 6 p.m., overwhelming temporary pumps that are supposed to keep the highway dry, according to Gilles Payer, a spokesperson for the agency.

Permanent pumping stations and water retention reservoirs have yet to be installed on the highway, he told CTV news. It was blocked for six hours Tuesday night.

"When the permanent pumping system and permanent retention ponds will be in operation, the risk of such an event will be virtually zero," Payer added. The systems are scheduled to be in place by the summer of 2020.

The intense rainstorm that hit Montreal Tuesday evening unleashed 40 mm of rain onto the city within two hours, according to Transports Quebec.

Montreal police said they received numerous calls about flooded homes and waterlogged roads.