Lee, a DAP leader, said she went there with an entourage of some 20 former and current municipal councillors and residents, wearing green shirts, but were stopped by a man in a black shirt after security checks were made by police at the scene.
At the time, somebody there shouted to her group, “Boss said you may not enter,” to which a member of Lee's group said she responded that they were only there for the food.
They were then charged at by about 30 to 40 people, who she claimed were BN supporters, who surrounded and roughed up four in her group, pinning them to the ground.
Lee said police at the scene tried to break up the fight, but were "powerless to stop the large group" of attackers.
"Since (entering politics in) 1993, this is the first time I felt protected by the police," Lee told Malaysiakini when contacted after the incident.
She feared that the situation could have been a lot worse had the police not stepped in.
Lee (in green T-shirt) said that when the thugs she described as "BN supporters" started their attack, Agriculture and Agro-based Industries Minister Noh Omar appeared and shouted, "Why are you here to cause trouble?"
One in her group replied, “We received a brochure. It says, 'all are invited.' We just want to eat, why not?"
An individual, who Lee alleged was an aide of Noh's, pushed her, causing her to lose her balance and injuring herself in the process.
Police eventually escorted Lee and her group, some of whom suffered bruises from the attack, out of the venue.
One member of the group, Lee said, lost a pair of spectacles while another lost a shoe in the fracas, but both of these were later recovered.
She said the five only suffered bruises, but the group was in a state of shock.
"They will undergo a medical examination and a press conference on the matter will be held tomorrow," she added.
Lee added they wore green shirts simply to show their support for Himpunan Hijau 2.0.
"However, we didn't plan to do anything at the ceremony. We just wanted to eat and then leave," she said.
Lee further explained that they received a brochure at their house that said all were invited to attended the ground-breaking ceremony.
Malaysiakini tried to contact Noh tonight but failed to reach him.
Speaking at the function later, Najib announced that two toll booths along the Grand Saga Highway would be taken off, effectively halving the charges for commuting in both directions.
Beginning midnight tonight, the Batu 9 toll booth on the Kuala Lumpur-bound route and the Batu 11 toll booth on the Kajang-bound route would cease operations, he said.
Najib also handed over a RM4.5 million cheque to the school for the construction of 36 classrooms, which will accommodate 1,500 pupils.
He also said that the 5.9-acre piece of land that the school would be built on, was worth RM20 million.