Thousands of metro riders were stranded Wednesday afternoon after three of Montreal's four lines were temporarily closed because of computer problems.
The orange line was shut down from one end to the other, just before 4 p.m.
Minutes later, public transit authorities announced the green line and blue line were closing for an indefinite period.
Transit riders took to Twitter to complain about the service stoppage, that happened on one of the year's hottest days.
Police were seen at the Lionel-Groulx hub station, directing people away from the underground platforms.
People complained about massive lineups at bus stops.
Service slowly resumed just before 5 p.m.