text: Fire Brigades Union (FBU) members walked out at 18:00 GMT on Friday and are due back on 4 November.
  Some fire brigades have warned the public could be left "vulnerable" and small fires may not be attended.
  Fire Minister Penny Mordaunt said fire and rescue authorities have "robust" plans in place for the weekend.
  Union officials say that under the government's proposals firefighters will have to work until they are 60 instead of 55, pay more into their pensions and get less in retirement.
  The proposals will leave firefighters at risk of dismissal as their fitness declines into their 50s, the FBU said.
  FBU members went on strike in England and Wales in August over the same dispute.
  Strike action due to take place in Wales has been averted after a "significant" change of direction by the Welsh government, the FBU said.
  General secretary Matt Wrack accused the Westminster government of "sickening hypocrisy".
  "The real scandal is that their own pensions are by far the most generous anywhere in the public sector," he said.
  One firefighter and his son carved pumpkins together and tweeted a photo in support of the strike.
  "It's an issue which affects both me and my family and I have explained the dispute to him," said the firefighter, who asked not to be named.
  The West Yorkshire brigade said the public would be left in a "vulnerable position" and asked people to take extra care this weekend.
  The London brigade said it may not attend rubbish or small grass fires or help anyone stuck in a lift.
  Industrial action over the past 18 months has seen fire authorities spend millions hiring contractors to cover for striking FBU members.
  The FBU said it expected about 36,000 firefighters to walk out.
  The fire minister said: "All fire and rescue authorities have robust and well-tested plans in place that include back-up support if needed.
  "Public safety is the primary focus and if anyone needs emergency assistance, they should dial 999."
  She said strike action was "unnecessary" after pension regulations laid in parliament on Tuesday mean nearly three quarters of firefighters will see no change in their pension age in 2015.
target: Firefighters across England are on a four-day strike in a row over pensions during one of the service's busiest weekends of the year.