The northbound side of the Louis-Hippolyte-Lafontaine tunnel will be fully reopened for Friday's morning commute from 5:30 a.m. until 9 a.m.

After 9 a.m., only one lane will be available so that crews can do some repair work, a spokeswoman from the Quebec Transport Ministry told CBC.

The span was closed Thursday, at around 9:30 a.m., after a fire broke out in an RV inside the tunnel

Almost six hours later, at around 3 p.m., the left lane was reopened.

Traffic remained very slow-moving in the area and other bridges connecting the city to the South Shore were also congested for several hours as vehicles were rerouted.

Transport Minister Robert Poëti says that about 10,000 feet of electrical wiring inside the tunnel was damaged in the fire. (Radio-Canada) Transport Minister Robert Poëti went inside the tunnel during Thursday's afternoon rush hour to meet with the crews on site.

"The damage of the tunnel looks more electrical. We're talking about 10,000 feet of electrical wires, for the lights inside, for about 500 metres. So I think it's going to be possible to reopen the tunnel tomorrow morning for the citizens travelling in the north direction."

Poëti said crews will then begin work to repair the electrical damage as of 9 a.m. — after the Friday morning rush hour.

RV catches fire

This motorhome caught fire while travelling inside the Lafontaine Tunnel on Thursday, Aug. 20. (Jay Turnbull/CBC) Transport Quebec confirmed the incident happened at about 9:30 a.m. Initially, the Sûreté du Québec said propane tanks on the RV had caught fire. Firefighters later said it was in fact the vehicle's engine.

No injuries were reported.

Mario St-Pierre, spokesman for Transport Quebec, said employees noticed there was a problem immediately via the ministry's traffic cameras. Work to clear the scene got underway immediately.

"There is a ventilation system that is in operation when there is such a fire so it's already in process," St-Pierre said Thursday morning, shortly after the incident happened. "It's providing good ventilation for such a situation like this while there is a fire in the tunnel."

The RV the caught fire inside the Lafontaine tunnel Thursday morning was pulling this chip wagon -- which contained 2 tanks of propane. The motorhome was hauling a chip wagon, which had 2 bottles of propane — one was 200 pounds.

According to a traveller's guide on the transport ministry's website, when driving inside a tunnel, one cannot be transporting "more than two gas cylinders (propane, butane) with a maximum capacity of 46 litres (about 40 pounds) each."

Firefighters had to scramble to put out the fire before it could spread to the propane bottles.

Vehicles trapped in the tunnel were released at around 11 a.m. By 12:30 p.m., tow trucks pulled the charred remains of the RV outside of the tunnel.

Crews were then able to get inside to assess the damage.

The southbound side of the tunnel was not affected.

The Montreal fire department is investigating the cause of the fire.