Police have fined four men after more than 50 flares were set off at a Melbourne spectator site where fans gathered to watch the Matildas’ Women’s World Cup semi-final against England.

Hundreds of fans flocked to Federation Square on Wednesday evening to cheer on the women in green and gold.

Police were constantly trying to ensure fans’ safety, but were no match against spectators, who breached temporary fences multiple times.

More than 50 flares were set off, with multiple being thrown into the crowd.

A Victoria Police spokeswoman said she wasn’t aware of anyone being injured.

“Overall, it was a challenging night for our members out at Federation Square, where we saw a large, rowdy group of mainly male youths, part of the active supporter groups, discharge and throw a significant number of flares,” she said.

Police doled out fines of more than $960 to four males, aged between 16 and 23, for possessing flares at Federation Square.

They also cautioned another 16-year-old boy for throwing a flare.

The spokeswoman said detectives would investigate the use of flares at Federation Square, and that police have secured CCTV of the incidents.

“We were very happy with the crowds at AAMI Park and at the many bars and pubs throughout the CBD and surrounding suburbs,” she said.

“There were no incidents of note at AAMI Park, other than a penalty notice issued to a male who was in possession of a flare.”

Fans are expected to gather at Federation Square again on Saturday to watch the Matildas take on Sweden in a bid to secure third place in the World Cup.

In NSW, fans endured long delays getting home from Sydney Olympic Park on Wednesday night after a suspected act of vandalism threw the rail network into disarray.

The incident at Ashfield affected trains from about 10pm, about the time the semi-final, which England won 3-1, wrapped up in front of a crowd of more than 75,000.

Two men aged 47 and 33 were assisting NSW Police with their inquiries after officers were told cables in a railway signal box were cut and equipment was damaged.

– AAP