BOSTON (AP) _ Under tight security, a 46-year-old man pleaded innocent today in the shooting deaths of four people killed this week in a crowded restaurant. His son and a third man have also been charged.

Anthony P. Clemente Sr. was arrested Tuesday inside the courthouse, where his son Damien was being arraigned. The father was arraigned today on the four counts of murder, assault with intent to murder and firearms violations.

Judge Anthony Sullivan ordered Clemente held without bail until his next court appearance Nov. 29.

``We are saying in fact he is one of the shooters,'' Boston Police Commissioner Paul Evans said Tuesday.

Damien Clemente 20, of suburban Medford and Vincent John Perez, 27, of Boston, pleaded innocent Tuesday to murder, assault and weapons charges. Both were arrested by two off-duty police officers Monday, seconds after running from a shooting at 99 Restaurant & Pubs in Boston's rough Charlestown section.

The dead included Robert Luisi and his son, Roman, his cousin, Anthony Sarro, and a friend, Anthony Pelosi.

Sarro's brother, Richard, staggered outside with a bullet in his stomach. He was discharged from Massachusetts General Hospital Tuesday night, spokeswoman Michele Marcella said.

Robert Luisi was reportedly a longtime mob associate aligned with a faction led by jailed New England mob boss Francis ``Cadillac Frank'' Salemme.

The Boston Globe, citing unidentified sources, said Luisi had been helping Salemme's brother, John, collect mob debts while Francis Salemme is in prison awaiting trial on federal racketeering charges.

Evans said police don't know the motive for the shootings.

WBZ-TV reported that Damien Clemente and Perez were dining at the restaurant when Luisi's group walked in. Clemente reportedly telephoned his father, who then came to the restaurant and walked directly to Luisi's booth, where he was joined by his son. The gunshots rang out soon afterward and diners dove for cover.

WBZ said Perez's gun was never fired. Police have refused to discuss the weapons used.

Perez, a clerk in a city tow lot, had a history of substance abuse and had been treated for depression, his attorney, Philip Tracy Jr. said. ``He feels very despondent for the pain that his family is going through now,'' Tracy said.

A judge has ordered him to undergo psychiatric testing.