POLICE say it would be "foolish" not to believe a spate of deliberately lit fires across the southern suburbs last night are not linked.

Investigations are continuing into a dozen fires that were lit between 12.30am and 3am this morning as police work to determine if it is one person or several behind the arson attacks.

"We've identified 12 (fires), there may well be other fires that we are not aware of," Superintendent Paul Bahr said.

"Several fires have been lit in close proximity of each other..... it would be foolish to suggest that they are not linked.

"I don't want discount that it could be one person, at the same time I don't want to discount it could be more than one person..... we have to keep an open mind."

A large contingent of firefighters were called in to fight one of blazes at Onkaparinga Hills, which was just 50m from Marianne Burke's home where she said she woke to a "wall of flames" about 3am.

"That was really scary to wake up to," Mrs Burke said.

"We just panicked and put all the roller shutters down and watched it."

Mrs Burke said it was concerning the fire had been deemed suspicious.

"It's scary but it's not surprising because we've had people light fires around here before," she said.

"It's an accessible area and it would be easy for someone to throw a match and drive off."

The fire burnt 4ha of scrubland and before it was contained.

Onkaparinga Hills resident and councillor Steve Webster said he thought there could be a connection to the spate of fires in late 2012.

"From the reports I have heard there is someone going around the city (lighting fires) so someone has got a beef,'' Mr Webster, said.

"It is important that neighbours are looking out for neighbours and that is the good thing about our community.

"I would like to see a ramp-up of Neighbourhood Watch in the area and a community meeting with police and the CFS would be a positive move.''

The first grass fire was called in by residents about 12.50am in Seaford Rise, near the waste depot, forcing emergency crews to close Bakewell Drive until they were able to extinguish the flames.

In the following three hours, crews responded to about 10 fires in McLaren Flat, Christies Beach, Onkaparinga Hills, Noarlunga and Morphett Vale.

A shed and machinery were destroyed by fire on a McLaren Flat property.

Onkaparinga mayor Lorraine Rosenberg said the southern suburbs had until today been relatively fire free over the dry and hot summer period.

"Then in just one night you get a spate of fires,'' Ms Rosenberg said.

"I think if the people doing this are seriously trying to do harm to the community they have got a criminal mind.

"And if they are trying to just cause nuisance value then they have absolutely no understanding of mother nature and what happens when a fire takes hold in these extraordinary dry conditions.''

The fires are the latest in a series of suspicious incidents.

Last week 40 firefighters attended a paddock fire at Hallett Cove, which burnt up to 12 hectares.

The grass fire last Wednesday at Perry Barr Rd took three hours to be extinguished by crews from the CFS and MFS.

The fires came amid blistering heat, with temperatures in the 40s.

All of the fires - in areas ranging from Onkaparinga Hills, Morphett Vale and Hackham - were deliberately lit.

The fires were started in targets such as rubbish, grass, bins and sheds.

The incidents last week were:

• A council bin at bus stop 58 on Doctors Rd, Hackham, was set alight at 12.20am on Tuesday.

• At 9.30am on Wednesday 4 sq m of grass on council land along a bike track in Ellis Ave, Morphett Vale, was burnt.

• Rubbish in the front yard of a house in Stirling Dr, Morphett Vale, was set alight about 12.10am on Wednesday.

• About 9pm last Wednesday, a vehicle drove away from States Rd, Onkaparinga Hills. The grass verge then immediately caught alight.

• Overnight on Wednesday, papers at the rear of a medical practice on Doctors Rd, Morphett Vale, were set alight.

• At about 1.30am on Friday a fire started in a carport in Argyle Ave, Morphett Vale, and spread to a neighbour's fence.

Investigators are seeking information from the public to help identify any suspects.

Anyone with information is asked to contact CrimeStoppers on 1800 333 000 or www.sa.crimestoppers.com.au