Ambulance crews in Lancashire have voted for strike action as part of a national dispute over pay.
Members of Unite, the GMB and Unison are staging a four-hour strike next Monday, October 13, between 7am and 11am.
It means only 999 calls will be responded to in that period.
And there will be industrial action short of strike for the rest of the week from 7am on Monday, October 13 to midnight on Friday, October 17.
Bosses at the North West Ambulance Service NHS Trust (NWAS) say they have not been told what the other action will be.
But we can reveal the action is a work-to-rule, which includes an overtime ban and staff working their exact hours.
Staff will be picketing ambulance stations in Lancashire throughout the four-hour strike, and union representatives will be in control rooms monitoring the exceptions they have agreed to attend.
Bob Parkinson, branch secretary for Unite at NWAS, said: “We are sorry we have been forced into this situation.
“We are not, by nature, a militant workforce and the staff are saddened to have to take this action.
“But year on year we have faced pay freezes and have seen constant attacks on the NHS, and we feel it is now time to voice our objections.
“We urge the health minister to intervene for the sake of patients and staff to resolve this issue.”
Today, ambulance bosses asked people not to call 999 unless in a real emergency.
Director of operations, Derek Cartwright said: “We respect the right for our staff to take industrial action, and we know that the decision will not have been easy.
“Our planning aims to ensure there is as little impact on patient care as possible and for this reason, we have maintained a healthy and lengthy dialogue with our trade union representatives.”
He added that talks were going on with the unions to try to “agree some exemptions”.
He added: “However, even with exemptions, with a reduced workforce, there is likely to be some disruption to the 999 service and delays in reaching patients.”
Patients who have out-patient appointments and have booked transport with the trust should contact their clinic and check that their appointment is still going ahead.
Midwives, radiographers and other public services will also be affected by the action across the public sector.