Police are searching more premises after two and a half tons of commercial explosives were found at a house in South Hills on Friday, Gauteng police said on Saturday.

"Investigations are ongoing and other premises are currently being searched. The possibility of more arrests cannot be ruled out," said Colonel Lungelo Dlamini.

Acting on a detailed anonymous tip-off from Primedia's Crime Line, members of the Gauteng Rapid Response Unit raided a house in Regina street in South Hills.

They found about 2500 kg of commercial explosives that was stolen from a depot in City Deep recently.

It was estimated that the value of the explosives seized were in the region of R134 000.

Two Zimbabwean nationals who were at the house during the raid, a man aged 22 and an 18-year-old woman were arrested and would be charged with contravention of the Explosives Act.

A third person was still at large.

Police also seized thousands of metres of explosives cord.

"The possibility that some of the explosives were used in recent ATM bombings is also being probed," Dlamini said.

Gauteng Police Commissioner, General Perumal Naidoo, who visited the scene, said he was "extremely delighted" at the breakthrough and praised the member of the public who used Crime Line to make the tip-off.

"This is an ordinary suburban home. The explosives were hidden in a bathroom almost up to the ceiling.

However, a vigilant member of the public kept his or her eyes open and blew the whistle. We praise and congratulate this person. We need more of this please."

Head of Crime Line, Yusuf Abramjee said it was encouraging to see more and more members of the public passing on detailed information to Crime Line. "We are also happy that the so-called 'big fish' are being targeted and nabbed. We congratulate the police force for their swift action and for this major bust."

Police have described the find a as a "massive breakthrough in the fight against ATM bombers."