* Hundreds of people wounded in two days of clashes
* Six dead after Sunday protests include three policemen
* Demonstrations have erupted in Port Said since January
* Security HQ, police cars set alight by protesters
* Detention of dozens after soccer riot spark demonstrations (Updates number of deaths, adds military statement, Port Said)
By Yousri Mohamed
PORT SAID, Egypt March 4 (Reuters) - Protesters hurled petrol bombs and stones at police officers who responded by firing teargas in Egypt's Port Said on Monday, a day after deadly demonstrations in the Suez Canal city.
Violent protests have erupted in Port Said since January over the detention of dozens of people after a soccer riot in the city last year in which 70 people were killed.
On Monday, hundreds of demonstrators gathered in front of a local government office to protest against the detentions and they set fire to two police cars, a witness said. The nearby headquarters of the security services was also set on fire.
Security forces fired teargas to disperse the crowds, and state news agency MENA said 35 people were injured in the clashes, including several hit by bullets.
Some 420 people have been wounded since the protests started on Sunday, about 60 from shotgun wounds and live bullets, said Sayed al-Masry, head of Port Said's ambulance service.
Three Egyptian policemen and three civilians died from wounds sustained during Sunday's clashes, security and medical sources said. The Interior Ministry said earlier in a statement two of its personnel died of bullet wounds to the neck and head.
The military, which described the clashes as "unfortunate" said in a statement on Facebook that the "great people" of Port Said were in the "heart and conscience of the armed forces".
It said it had made a promise to protect people and their property "whatever the sacrifices".
Egypt has been in political turmoil for the last two years since a popular uprising ousted President Hosni Mubarak.
His Islamist successor, Mohamed Mursi, has struggled to restore security since he was elected in June. Some 60 people died during a string of violent street protests between Jan. 25, the anniversary of the revolution, and Feb. 4 this year.
A perception among some Egyptians that Mursi and his Muslim Brotherhood are trying to monopolise power has fuelled some demonstrations, as has a more general sense of political and economic malaise. (Additional reporting by Marwa Awad and Alexander Dziadosz in Cairo and Amr Dalsh in Port Said; Writing by Sylvia Westall; Editing by Louise Ireland)