London firefighters are due to hold talks with brigade officials in a bid to end a row over new contracts.
More than 5,500 firefighters took part in a second eight-hour strike on Monday over claims they face "mass sackings by the end of the month".
London Fire Brigade has said changes were needed to make time for "vital training and fire prevention work".
If the talks fail fire crews plan to stage a 47-hour walk out on Friday, which is Bonfire Night.
Private contractors responded to 20 callouts, including eight fires, between 1000 and 1800 GMT on Monday, London Fire Brigade (LFB) said.
During the strike two men were taken to hospital after being hit by vehicles on picket lines in Croydon and Southwark.
Two men were arrested over the incidents and have since been released on bail.
A man, thought to be a demonstrator in his 40s from Edenbridge, Kent, was injured when he was hit by a car outside Croydon fire station at about 1520 GMT.
He was taken to hospital with pelvic injuries and the union's president, Mick Shaw, said the man had "rolled on to the bonnet, then rolled off" the vehicle.
At about 2100 GMT, FBU representative Ian Leahair needed minor treatment after being hit by a fire engine outside LFB's training centre on Southwark Bridge Road.
The FBU said a third person was hurt near the centre on Southwark Bridge Road when a fire engine hit his hand.
Cover during the strike was supplied by private firm AssetCo, which signed a £9m seven-year deal with LFB last year.
It was using 27 fire engines and 170 contract workers.
Originally the brigade wanted to end the current nine-hour days and 15-hour nights and bring in equal 12-hour day and night shifts.
LFB has now offered firefighters to do 11-hour day shifts and 13-hour night shifts, but this has been rejected by the union.
The dispute centres around the brigade asking firefighters to sign a new contract to bring the shift changes into effect.
The union said firefighters faced the sack if they did not agree to this.