Bobby Linn, Kevin Buchan and Simon Murray netted for the hosts before Graham Webster's consolation. Montrose's Declan O'Kane was sent off before the end.
Marc McKenzie curled in a superb 80th-minute winner as Albion Rovers beat visitors Queen's Park 1-0.
Berwick Rangers drew 3-3 at Clyde. John Fairburn fired Berwick ahead but Scott McManus levelled. After the break, Berwick took command with goals from Lee Currie - later red-carded - and David Gold but McManus and Michael Daly responded.
Annan Athletic got their first point in a 3-3 home draw with Elgin City. Josh Todd and Kenny MacKay scored for Annan either side of a Marvin Andrews goal.
Craig Gunn made it 2-2 with a 53rd-minute penalty and Archie MacPhee put the visitors in front but Derek Carcary rescued Annan.
East Fife beat East Stirling 3-1 thanks to goals from Jon McShane, Kevin Smith and David Maskrey.