The first emergency alert mentioning Yarloop by name was issued just 25 minutes before a bushfire razed the Western Australian town, with earlier alerts just listing the names of roads that encircled the town, the state’s fire authority has confirmed.

Residents of the heritage-listed town, 125km south of Perth, have criticised the Department of Fire and Emergency Services (DFES) for failing to warn them that the fire front was coming on Thursday night, with some saying the only warning they received was an automated text about the Waroona fire, then about 20km to the north, on Wednesday.

In a statement issued late on Monday, DFES said the first emergency alert explicitly mentioning Yarloop was issued at 7.35pm on Thursday. The fire hit the town at about 8pm.

However, DFES said that three earlier alerts, the first issued at 8.25pm on Wednesday, the first day the fire was reported, included parts of the Yarloop townsite in its broader description of the fire area.

That description was given by listing roads that served as a boundary to the area considered to be at risk. Maps accompanying DFES’s statement show that by 5.55am on Thursday, most of the Yarloop townsite was included in the alert area – but that was stated only by listing the boundary roads, not by mentioning Yarloop by name.

Emergency alerts are posted on the DFES website and social media channels, read out on ABC local radio, and issued to media outlets.

The fire and emergency services commissioner, Wayne Gregson, earlier said he didn’t know when the first warnings mentioning Yarloop were issued, but that would not have prevented residents in the town from knowing about the bushfire. “It is incomprehensible to me that people would say, well, I didn’t know that there was a fire on my doorstep,” he said.

The statement from DFES repeated that theme of personal responsibility, saying: “in the event of a bushfire, DFES advises all members of the community to stay aware of their surroundings and take appropriate and early action for their safety”.

“Leading up to and at the time of impact, it can be confirmed that there were numerous fire appliances and earth-moving equipment within and around the townsite of Yarloop,” the statement said.

“Over the four-day period [from Thursday to Sunday] the community was advised, every hour, to take action – either leave the area or be ready to actively defend their homes.”

DFES said the majority of the town’s population of 540 decided to leave on Thursday, but about 150 remained behind. Many sheltered on the oval, protected by the fire trucks of local brigades.

Firefighters who remained to help have said the fire took just 10 minutes to flatten the town, with 143 buildings, including 128 homes, destroyed. Two elderly male residents, 77-year-old Les Taylor and 73-year-old Malcolm Taylor, not believed to be related, died in the fire. David Phillips, a Yarloop resident who tried to save Les Taylor, has laid part of the blame on the lack of warnings, saying “no one said anything about Yarloop”.

DFES said a decision was made not to send in police to door-knock the area, because “it was deemed unsafe to send non-firefighting personnel into the Yarloop area on Thursday evening to individually direct remaining community members to evacuate.” Police did door-knock houses in Harvey, 15km to the south, on Saturday, despite the order to evacuate being given on Friday.

Authorities have also been criticised for the lack of water in Yarloop, which firefighters have said left them unable to defend properties.

Scott Britza, a volunteer firefighter from Harvey fire and rescue service, told Fairfax Media his crew was left with just 500 litres of water to defend themselves and residents on the oval.

Sue Murphy, chief executive of the Water Corporation, has confirmed that the feed-in supply to Yarloop’s water tank was cut off at 7.26am on Thursday when the town lost power. Murphy said the tank was full at that time but couldn’t be replenished. The town’s fire hydrants remained operational.

“Water Corporation works closely with DFES in the event of a bushfire so that firefighters have the best access to available water supplies,” she said. “Despite these efforts, there will often be a total loss of water.”

The standing advice from DFES and the Water Corporation is that people planning to stay and defend their home in a bushfire should have an independent water supply and a fire pump that doesn’t rely on mains electricity.

The fire was stopped just 1km from the Harvey town boundary on Sunday and is currently behind containment lines, although Gregson warned that there were still pockets of fire along the fire’s 232km perimetre which could flare up if weather conditions changed.

That could happen as soon as Friday, with temperatures of 37C and dry thunderstorms forecast for the south-west.

Murray Cowper, a Liberal MP whose state electorate includes the fire zone, said it could take months until the fire is extinguished and firefighters – both in managerial positions in DFES and volunteers – needed ongoing support.

“They have been fighting for days on end. Now is not the time to be pointing fingers and playing the blame game, now is the time to pull together,” he said.