Ryan Dow put the home side in front, but Jamie Gullan had Saints level before the break.

Liam Smith’s header then looked to have turned the match around, but Thomas O’Brien soon had Arbroath back level again at 2-2 when he nodded in from a free-kick in the 58th minute.

Josh Fowler struck a third for St Johnstone in the 66th minute and Jack Baird headed in a fourth with 15 minutes left.

Saints now sit five points clear of Partick Thistle, who were held to a 1-1 draw at Ayr, finishing with 10 men.

Thistle had defender Lee Ashcroft sent off for a second yellow card just before the hour mark.

The visitors, though, went in front with 20 minutes left through Cale Loughrey following a corner.

Ayr secured a point with 13 minutes left when Jamie Murphy scored a penalty after Loughrey had brought down Anton Dowds.

Airdrie hauled themselves off the bottom with a 4-0 win at fellow strugglers Ross County.

Lewis Strapp nodded Airdrie into an early lead, with further goals from Chris Mochrie, Cole McKinnon and Adam Devine putting the game out of reach for County, who drop to the foot of the table.

Dunfermline came from behind to beat Greenock Morton 3-1 at East End Park.

Cameron Blues had given the visitors a half-time lead, but Andrew Tod equalised early in the second half.

Kieran Ngwenya and Matthew Todd completed the turnaround as Dunfermline moved within four points of third-placed Arbroath.