Tehran, Iran (CNN) -- The head of a security team protecting opposition leader Mehdi Karoubi was in a coma Thursday after being beaten as he tried to talk with a group of attackers who had entered Karoubi's apartment building, Karoubi's website said.
The website, Saham News, said the security team leader, whom it identified as Mr. Yari, was taken to a hospital.
The attackers shot at the building, cut water pipes to the apartment and tried to cut power on the street, it said.
"Regretfully, the disciplinary forces have left the site completely," it added.
The website identified the attackers as members of the Basij, militia who support Supreme Leader Ayatollah Ali Khamenei, and said Thursday was the fourth consecutive night that Karoubi's apartment had come under attack.
It said that Karoubi's bodyguards shot into the air after the Basij broke the door to the building, forcing them back.
Karoubi's son, Mohammad Taghi Karoubi, told CNN he was inside his father's fifth-floor apartment when about 20 Basij broke into the courtyard of the complex and fired shots, set small fires in the courtyard and the lobby and vandalized parts of the building.
"They called the police; nobody came," he said.
Asked who was responsible, he said, "They are in the name of the Basij, but in my opinion they are hooligans. The government tries to use these hooligans against the opposition and against the people."
Karoubi said he heard several of the men say they were there to kill his father.
He said his father's security detail pleaded with the gathering to stay outside the building to no avail and added that several of his father's security team were injured -- but not shot -- and were taken to a hospital.
Police were aware of the situation but did nothing to help, he said.
Asked if he and his father planned to attend Quds Day events on Friday, he said, "Do you think we'll still be alive tomorrow morning?" Quds Day demonstrations are an annual event intended to show Iran's solidarity with Palestinians.
Government forces put down massive protests that erupted after last year's June election victory by President Mahmoud Ahmadinejad in a vote regarded as fraudulent by many.
Karoubi said the thugs remained outside his father's door and added that the elder Karoubi had no plans to leave.
CNN could not confirm the reports.