Noel Gallagher plays at the 2008 Virgin Music Festival. He was assaulted during the song (What's the Story) Morning Glory? (Dwight Friesen/CBC)

A man was charged with assault on Monday after the Gallagher brothers of Oasis were attacked while performing at the annual Virgin Festival in Toronto on Sunday.

Guitarist Noel Gallagher was treated in hospital after a man ran onto the stage and attacked him while he and his brother Liam were performing, according to the band's website.

Noel Gallagher "fell heavily onto his monitor speakers," and may have fractured his rib and suffered ligament damage, the site said.

Now the band says it may have to cancel its concert slated for Tuesday in London, Ont. The band is asking fans to keep checking the Oasis website for updates.

Daniel Sullivan, 47, of Pickering, Ont., was charged with one count of assault on Monday in a Toronto court. He was released with a promise to appear in court Oct. 27.

Police say a man may have come from the wings of the stage or jumped up from the crowd of 25,000 at the final performance of the festival on Toronto Island on Sunday night.

The man tackled Noel Gallagher and then went after his brother Liam, who was halfway through singing the band's hit (What's the Story) Morning Glory?

Liam raised a fist and appeared to be ready to hit the man before security grabbed the attacker.

'Stunned' silence follows attack

"Someone barged out from the back and hit someone. It all happened so quickly that I wasn't in a position to evaluate who was doing what to whom," said David Lee, who was in the audience.

Lee told CBC News on Monday that the crowd went quiet after the attack.

"I supposed one word to describe that is they were stunned into silence," said Lee, 53, who has been to many concerts, but never seen such violence before.

The attacker was quickly pulled off stage after launching the assault, and the Gallagher brothers also left. After about five minutes though, Noel returned and led the band through another song. Liam then emerged to sing the band's hit Wonderwall.

Lee was filming the concert on his digital camera when the incident occurred. He decided to keep filming, realizing that from his seat 15 to 25 rows back, he could see better through the zoom lens of his camera than with his own eyes.

He later decided to post the video on You Tube, and by 6 p.m. ET Monday it had been viewed more than 290,000 times.

"I wanted to make sure that people who weren't there had the opportunity to evaluate for themselves what exactly happened, rather than rely on rumours," Lee said.

"The band itself is a significant player on the music scene. This is an act of injustice, an uncalled for attack on anybody, regardless of who they are."

The concert ended at 10:30 p.m. ET, much earlier than anticipated, with a cover of the Beatles' I Am the Walrus.

The band's North American tour wraps up in New York City on Sept. 12.