KwaZulu-Natal police spokesperson Captain Nqobile Gwala said police were investigating three counts of attempted murder and arson.
One of the victims died and the other two are now in critical condition. "The other two are in critical condition", said Balram, adding that the suspects fled in a white vehicle.
He said "multiple patients have been stabbed" and the mosque had been set alight.
He reportedly said the attackers accused the men of "brainwashing people".
"They allegedly attacked three people and stabbed them".
Local media reported on Friday that the victim was the mosque's imam and that he was from Canada but Mhlongo could not confirm those details.
The motive for the attack was still not known. About 1.5 percent of the country's population is Muslim.
Social activist Yusuf Abramjee said he had seen information being circulated online that the attacked mosque belonged to the Shia sect. "He was treated by paramedics on the scene and transferred [to a hospital]". "One knife was left behind", Prem Balram, spokesman for Reaction Unit South Africa said, speaking from the scene.
He said a third victim had been attacked inside the building, which was then set alight, and had jumped out of a window.
Speaking further, the representative noted that there had already been theft and robbery incidents at the mosque before.
"A mosque is a religious institution‚ and South Africa's Constitution guarantees and protects the right to religious practices‚" he said. "Speculation about the motive is quite risky at this point".
The chairperson of the portfolio committee on police, Francois Beukman also condemned the attacks.