It was after a match in the country's top division Liga 1 between Arema and Persebaya Surabaya that violence broke out.
The home team Arema lost 2–3 and disgruntled supporters stormed the pitch after the final whistle, writes the Indonesian football association PSSI on its website.
The stadium holds 42,000 spectators and is said to have been sold out.
According to the police, there were around 3,000 people who stormed the pitch.
Many were trampled to death
Police have described the events as riots and used tear gas to try to disperse the thousands of people who stormed the pitch.
Many of the dead were trampled to death according to the police.
The incident has received a lot of attention in large parts of the world, and now Gianni Infantino, who is president of the International Football Association (FIFA), has made a statement.
- The football world is in a state of shock after the tragic incident, he says on Fifa's website.
- This is a dark day for everyone involved in football and is a tragedy beyond comprehension.
I send my deepest condolences to the families and friends of the victims who lost their lives in this tragic incident.
U20 WC next year
SVT Sport has been in contact with Fifa, who do not want to give any further comments than Infantino's above condolences.
Among other things, we asked how Fifa will act in the future, and whether the current events may affect the U20 World Cup to be played in Indonesia next year.