One of Gadhafi's sons killed in NATO airstrike,

Tripoli, Libya (CNN) -- One of Libyan leader Moammar Gadhafi's sons -- Saif al-Arab Gadhafi -- was killed after a NATO airstrike, a spokesman for Libya's government said Sunday at a press conference.

Moammar Gadhafi and his wife were in their son's house when it was targeted, spokesman Musa Ibrahim said. Both of them are in good health, according to the spokesman.

The victim is one of two Gadhafi sons whose names begin with Saif. The other is Saif al-Islam Gadhafi, who had previously touted reform but has emerged as one of his father's most visible defenders in recent months.

Ibrahim said several of Moammar Gadhafi's grandchildren also died in the attack.

The house in Tripoli was destroyed by the strike, with a massive crater where the house used to be. At least one unexploded bomb could be seen.

The building was in a residential area of Tripoli, according to Ibrahim, who insisted that Saif al-Arab Gadhafi was a student in Germany who was not deeply involved in Libya's military and government. The 29-year-old was the sixth of Gadhafi's eight biological children.

Ibrahim railed against NATO after the fatal strike, calling it an illegal act and a "war crime." He vowed revenge.

Speaking at a rally, Ibrahim told fellow Libyans, "Every one of you are Saif al-Arab."