Mati, Greece (CNN) There are "serious indications of arson" in one of several Greek wildfires that killed more than 80 people this week, authorities said Thursday.

Nikos Toskas, deputy minister for citizen protection, said the belief is based on satellite images and ground inspections by police and fire officials at the scene of a deadly blaze that started in the town of Penteli in east Attica.

More than 15 fires broke out on three fronts in that part of southern Greece on Monday afternoon, according to government spokesman Dimitris Tzanakopoulos, who described the challenge to firefighters as unprecedented.

The mayor of the municipality where more than 80 people lost their lives to wildfires has admitted that mistakes were made in the response to the crisis, telling CNN that no evacuation order was given and that the scale of the fire was "underestimated."

Vagelis Bournos, mayor of Rafina-Pikermi, said that although weather conditions including very strong winds had played a major role, human error was partly to blame for the deaths, citing the lack of a warning as well as longer-term problems including poor urban planning and the impact on public services of years of austerity.

"We might have had less victims with a well-organized evacuation plan but when the fire began in the municipality of Penteli there was no evacuation order for the east part (of Attica) because of the direction of the wind," Bournos told CNN in an interview Wednesday, adding: "The fire was underestimated."

But the mayor also defended the decision not to evacuate Mati and the surrounding coastal villages, where hundreds of homes were gutted in the blaze that tore through the area Monday.

"Citizens do not follow evacuation plans but they stay behind to protect their households," he said.

"Of course there is anger due to the fact that there are victims. But the same people who are angry now, when the evacuation order would have been issued, they would have stayed back and tried to protect their houses. So victims would still be there, a smaller number, but still."

A number of bodies were found in cars and close to the sea, however, suggesting that many residents did attempt to flee. Hundreds more made it to the beaches and rocky coastline, some waiting in the sea for hours before being rescued.

Demetres Karavellas, director general of WWF Greece, which has warned for years of the deadly threat posed by wildfires and often advises local authorities on how to regenerate areas after fires, described the mayor's reasoning as "a lame excuse."

"People were trying to leave, people were trying to get out," he told CNN on Thursday.

Bournos admitted that there was a window of time in which an evacuation order could have been issued, but it was missed. By the time the blaze was close to Mati, "practically, there could not have been an evacuation," he said. "The decision would have had to have been made a couple of hours earlier."

"We could have made better decisions for sure," he said.

Photos: Deadly wildfires ravage Greek towns Firefighters and volunteers try to extinguish flames in Kineta, Greece, on Tuesday, July 24. Hide Caption 1 of 28 Photos: Deadly wildfires ravage Greek towns An injured woman is carried by a rescue crew in Mati on Wednesday, July 25. Hide Caption 2 of 28 Photos: Deadly wildfires ravage Greek towns Dinnerware destroyed by the fire is seen inside a house in the village of Neos Voutzas on July 25. Hide Caption 3 of 28 Photos: Deadly wildfires ravage Greek towns A firefighting helicopter drops water in Kineta on July 24. Hide Caption 4 of 28 Photos: Deadly wildfires ravage Greek towns Asimina Psalti, 87, sits outside the remains of her burned house in Mati on July 24. Hide Caption 5 of 28 Photos: Deadly wildfires ravage Greek towns Firefighters try to extinguish flames in Kineta on July 24. Hide Caption 6 of 28 Photos: Deadly wildfires ravage Greek towns An aerial view shows buildings destroyed in Mati on July 24. Hide Caption 7 of 28 Photos: Deadly wildfires ravage Greek towns Emergency workers remove a victim's body in Mati on July 24. Hide Caption 8 of 28 Photos: Deadly wildfires ravage Greek towns A partially melted car sits on a road in Mati. Hide Caption 9 of 28 Photos: Deadly wildfires ravage Greek towns A firefighter is seen with a dog that was rescued from a burning house in Mati. Hide Caption 10 of 28 Photos: Deadly wildfires ravage Greek towns People watch as a helicopter collects seawater to fight the wildfires in Mati. Hide Caption 11 of 28 Photos: Deadly wildfires ravage Greek towns Emergency workers arrive in the area where victims' bodies were discovered in Mati. Hide Caption 12 of 28 Photos: Deadly wildfires ravage Greek towns A man tries to dampen the flames in a blazing building near Athens. Hide Caption 13 of 28 Photos: Deadly wildfires ravage Greek towns A house burns in a wildfire in Kineta on Monday, July 23. Hide Caption 14 of 28 Photos: Deadly wildfires ravage Greek towns Rescuers and volunteers help residents evacuate Mati on July 23. Hide Caption 15 of 28 Photos: Deadly wildfires ravage Greek towns People watch as a wildfire takes hold in the town of Rafina on July 23. Hide Caption 16 of 28 Photos: Deadly wildfires ravage Greek towns Two women evacuate Mati on July 23. Hide Caption 17 of 28 Photos: Deadly wildfires ravage Greek towns A man tries to put out flames in Kineta. Hide Caption 18 of 28 Photos: Deadly wildfires ravage Greek towns People enter the water to escape the flames on a Mati beach. Hide Caption 19 of 28 Photos: Deadly wildfires ravage Greek towns A fire smolders at a beach facility in Kineta. Hide Caption 20 of 28 Photos: Deadly wildfires ravage Greek towns A firefighter takes on a wildfire hotspot in Kineta. Hide Caption 21 of 28 Photos: Deadly wildfires ravage Greek towns The fire causes a huge traffic jam near Kineta as people try to escape the flames on July 23. Hide Caption 22 of 28 Photos: Deadly wildfires ravage Greek towns A firefighter reacts as a house burns in Kineta. Hide Caption 23 of 28 Photos: Deadly wildfires ravage Greek towns People escape to the seaside in Kineta. Hide Caption 24 of 28 Photos: Deadly wildfires ravage Greek towns Smoke fills the sky as emergency workers block a road near Kineta. Hide Caption 25 of 28 Photos: Deadly wildfires ravage Greek towns A motorcyclist passes burning brush on a road near Kineta. Hide Caption 26 of 28 Photos: Deadly wildfires ravage Greek towns Smoke rises over Athens' ancient Acropolis hill on July 23. Hide Caption 27 of 28 Photos: Deadly wildfires ravage Greek towns Tourists leave the Acropolis after authorities decided to close the archaeological site as a precaution. Hide Caption 28 of 28

'An accident waiting to happen'

Bournos' admissions also suggest a lack of coordination in the response, which Karavellas said is a chronic problem across Greece.

"Coordination has always been an issue," he said. "We saw this in the wildfires of 2007 which was the last fire that had such a high death toll. Back then, we saw the same situation we see now -- a problem of coordination when the fire breaks out: no evacuation plan in place and nobody centrally coordinating."

A Mati resident who did not want to be named out of fear he would get in trouble with the local authorities told CNN on Wednesday that locals had been requesting preparedness plans for wildfires for several years to no avail. "This was an accident waiting to happen," he said.

Bournos confirmed that residents had made such requests and said that plans had been produced by local volunteer firefighting organizations, but only for smaller-scale scenarios.

Fires across Greece caused dozens of deaths in 2007. Demetres Karavellas says that few lessons were learned from that disaster.

Escape routes blocked

The geography of Mati and the surrounding area is also emerging as a key factor in the high death toll. Many houses were built haphazardly and with little regulation in forested areas and were therefore extremely vulnerable as fire ripped through the dry woodland, which consisted mostly of highly flammable pine trees.

Added to that, roads in the area are narrow and unsuited for large numbers of cars, according to Bournos.

"We are talking about a densely populated area that was built without any urban planning," Bournos said. "Streets were not designed for such heavy traffic ... four thousand households and their residents tried to use streets that couldn't fit them all in."

Burnt cars are seen in Mati following the wildfire.

Residents spoke of being unable to leave the area by car as the fire approached because of congested roads. Photographs taken later showed streets blocked by abandoned, burned-out cars, some with doors left open, suggesting people who were unable to drive out of Mati had decided to flee on foot instead.

Asked if authorities would be more prepared in the future if a similar fire were to hit the Mati area again, Bournos said, "There is nothing left to be burned now. Nature and houses have been totally destroyed. We are here, committed to rebuilding everything the way it was, but now with infrastructure."

A satellite image of Mati taken in October last year shows how many houses were surrounded by flammable forest.

Lack of firefighting resources

Bournos cited the lack of sufficient firefighting forces as a problem. A second set of fires that broke out almost simultaneously in Kineta, around 80 kilometers (50 miles) from Mati on Attica's western coast, drew resources, Bournos said, leaving fewer available to fight the flames in eastern areas.

He also blamed the national austerity policies of the last few years, which have resulted in cuts to all public services.

A firefighter works to quell the blaze in Kineta, west of Athens Monday.

But both Bournos and Karavellas cite the unusually extreme weather conditions that contributed to Monday's disaster -- high temperatures, strong westerly winds (a rare phenomenon in the region) and a dry winter that created tinderbox conditions.

As the global climate continues to change, this type of fire will become more likely, Karavellas warned.