Australia vowed stricter gun laws on Monday as it began mourning victims of its worst mass shooting in almost 30 years, in which police accused a father-and-son duo of killing 15 people at a Jewish celebration at Sydney's famed Bondi Beach, Reuters reported.

The incident has raised questions about whether Australia's gun laws, among the toughest in the world, need an overhaul, with police saying the older suspect had held a firearms license since 2015, along with six registered weapons.

Prime Minister Anthony Albanese said his cabinet agreed to strengthen gun laws and work on a national firearms register to tackle aspects such as the number of weapons permitted by gun licenses, and how long the latter are valid.

Of the two gunmen, the 50-year-old father was killed at the scene, taking the tally of dead to 16, while his 24-year-old son was in critical condition in hospital, police told a press conference.

National broadcaster ABC and other media identified the men as Sajid Akram and his son Naveed Akram. Home Minister Tony Burke said the father arrived in Australia in 1998 on a student visa, while his son is an Australian-born citizen.

Two flags of the ISIL terrorist group were found in the gunmen's vehicle, ABC News said, without citing a source.

A bystander whose refugee parents had just arrived from Syria, Ahmed al Ahmed, captured on video tackling and disarming an armed man during the attack, has been hailed as a hero whose action saved lives.

He went under surgery after being shot twice. A fundraising page drew more than A$1,000,000 ($665,000) for him.