There are growing fears after the latest underworld attacks on popular Melbourne nightspots.

One was peppered with bullets, while a Chapel Street bar was engulfed by flames in an arson attack.

A fireball erupted outside Bar Up on Chapel Street just before 5am.

A fireball erupted outside Bar Up on Chapel Street just before 5am.© Nine

One witness said they were trying to get inside the door.

It’s understood the owner was inside at the time and tried to extinguish the blaze using a hose before being forced to flee.

Almost two hours earlier police say several shots were fired at the Emerson in South Yarra.

It’s the third time it’s been targeted this year.

Earlier this month it was torched and in February it was ram-raided before being set alight.

The bar and nightclub was open at the time of the shooting, which unfolded just before 2am.© Nine

Nine News understands a new crime syndicate is believed to be behind the spree.

Police are investigating whether scare tactics and extortion are being used to gain a stronghold on the booze market.

Former detective Charlie Bezzina said: “Criminal gangs are moving on from tobacco, now into alcohol, they’ve obviously seen an easy dollar to be made.”

Yesterday it was Bar Bambi, with three teenage boys charged after an arson attack.

“The fact that they’re engaging possibly the junior people, the youth, to get paid a small amount to conduct the arson attacks is so worrying,” Bezzina said.

The owners say the latest attack won’t deter them from operating as normal, taking to social media to reassure patrons safety is a priority.

Multiple shots were fired into The Emerson just before 2am.© Nine