Australian police say operation at Sydney Opera House concluded

Australian police said on Thursday that a police operation in Sydney has been concluded.

Police carried out operations at the Sydney Opera House and Manly, a beach suburb 15 kilometres north of the city's central business district, shortly after 0300 GMT, with the operations concluded about one hour later."Following information on social media, police conducted an operation in the vicinity of the Opera House and Manly as a precautionary measure," New South Wales police said in a statement. 

Fairfax Media reported the operation was sparked by a bomb threat on board a Manly ferry. According to the Sydney Morning Herald, NSW trasport stated a ferry from  Manly to Circular Quay at 1.20 p.m was cancelled due to the operation, while the others on the same route were delayed.

No further details were provided on the nature of the operation.

Australia is on heightened alert for attacks by home-grown militants. Authorities say they have thwarted a number of potential attacks, although there have been several "lone wolf" assaults.

Many around the area took to twitter to share some of the scenes as people were being evacuated:

All workers from the Opera house now outside away from the building #Sydney @abcnewsSydney pic.twitter.com/GOytxXBjqt

— Scott Lilleyman (@scotty_rockstar) January 14, 2016

Staff and tourists sit behind police line pic.twitter.com/tiei5Qyenn

— brad esposito (@braddybb) January 14, 2016

Opera Bar staff sitting around outside, they were told to evacuate ten mins ago, say they haven't been told anything pic.twitter.com/pCP2tp0C8i

— Alex Lee (@alex_c_lee) January 14, 2016

Police boat patrolling the front of the Opera House! I can see police walking through the buildingNeutral Bay Ferry pic.twitter.com/d5JfFgM1M2

— Scott Lilleyman (@scotty_rockstar) January 14, 2016