At least 10 people were killed and many more injured in a school shooting in Brazil's largest city Sao Paulo on Wednesday.

Among the dead are seven students, a woman and the two shooters, who killed themselves at the scene, authorities said.

The shocking attack took place at 9:30 a.m. local time (1230 GMT) at the Raul Brasil Public School in the Jardim Emperador neighborhood of Suzano, a community located within the greater metropolitan area of Sao Paulo.

Initial reports said eight people were killed, but the death toll rose as several succumbed to their injuries after 17 people were wounded and taken to hospital.

The attackers used firearms and knives, sparking a stampede as panicked students ran for cover.

A bomb squad was dispatched to the school, as witnesses reported seeing the two attackers enter the premises carrying a large bundle of cables and feared it could contain explosives.

Parents and neighbors desperate for news arrived at the school.

"These are the worst scenes I have ever seen in my life," Sao Paulo state Governor Joao Doria told reporters at the scene, adding the priority was to attend to the victims and their families.

Military Police spokesperson Cibele da Silva said there were "several injured people who were taken to two area hospitals," some in serious condition.

Nearly 1,000 students attend the elementary and junior high school in two shifts.