(CNN) -- A mob ransacked the entrance to the Tehran apartment complex of Iranian opposition leader Mehdi Karrubi late Thursday, an assault that resulted in an attack on the head of his security detail, his son said.
"Our situation is not good at the moment," Mohammad Taghi Karrubi, Karrubi's son, told CNN.
People have demonstrated in front of his house for four straight days, the son said. Demonstrators gathered outside and chanted for the first two days, but late Thursday a mob broke into the building.
About 40 to 50 demonstrators returned on Friday. Many, armed with guns and paintball guns, surrounded the house Friday and shouted chants against Karrubi and the opposition movement.
Karrubi's security personnel told the leader to shun Friday's Quds Day events, fearing for his safety and Karrubi has agreed, his son said.
Late Thursday, the son said, demonstrators attacked the apartment building with guns and tried to set the doors on fire. About 20 to 25 people entered the lobby and the entrance in the first floor but did not reach other floors of the apartment.
The son said the head of his father's security team tried to talk to the demonstrators and "told them if you want to say everything, if you want to attack the house, breaking the window, putting the fire on the door, you can do it but you're not allowed to come inside the house with guns and with tear gas."
But, the son said, the demonstrators came in and the police that were asked to help did nothing. He said the head of his father's security was injured when no one came to help him. Karrubi's website said the security official was in a coma after attackers beat him.
"That's a problem," said the younger Karrubi, referring to the lack of police response.
"My dad's flat is OK right now but we don't know about the future," the son said, who added that his father was in the flat at the time and was not harmed as the people shouted for his death.
"He says he's not going anywhere and he says he's ready to sacrifice myself," the son said.
The Karrubi website identified the attackers as members of the Basij, militia who support Supreme Leader Ayatollah Ali Khamenei. Karrubi's son said the people are doing this in the name of the Basij, but he believes they are simply "hooligans."
"I am so sorry to talk about this and say they are the Basiji or, I don't know, volunteers because I was a member of the Basij during the Iran-Iraq war and I did many years in the Basij during the Iran-Iraq war," he said. "The government tries to use these hooligans against the opposition and against the people."
He said that Karrubi's bodyguards shot into the air after the demonstrators broke the door to the building, forcing them back.
When asked on Thursday whether Karrubi would take part in the Quds Day event, the son responded, "Do you think we'll be alive tomorrow morning to take part?"
An annual event intended to show Iran's solidarity with Palestinians and opposition to Israel's policies, Quds Day is marked throughout the Muslim and Arab world and elsewhere with anti-Zionist demonstrations. The day is held on the last Friday of the holy month of Ramadan, but it is a political and not a religious event. Quds means Jerusalem in Arabic.
The day happens to fall as Israelis and Palestinians are involved in direct peace talks in Washington.
Government forces put down massive protests that erupted in Iran after last year's June election victory by President Mahmoud Ahmadinejad in a vote regarded as fraudulent by many.