Story highlights Parents want to make statement about injured boy

Rights group says teen was injured by tear gas canister

Security forces break up speech, go after demonstrators

Officials cannot be reached for comment

Turkish riot police used batons, water cannons and chemical sprays to prevent the parents of a wounded 14-year-boy from making a public statement about their comatose child.

Sami Elvan and his wife, Gulsum, gathered Wednesday evening with several dozen supporters in Istanbul's central Taksim Square.

"The reason we wanted to make the press statement was because so many people have been asking about my son's situation," Elvan told CNN after the small gathering was dispersed.

"I don't want anything, I just want the murderer of my child," cried Gulsum as she arrived in the square to make her statement.

The Elvan family said they last saw their son, Berkin, conscious on June 16, when he left their apartment in a working-class neighborhood in central Istanbul to buy a loaf of bread.

The previous night, riot police had clashed with demonstrators in this Okmeydan district of Turkey's largest city, during a wave of the biggest anti-government protests Turkey has seen in more than a decade. The clashes continued into the next day.

Sami Elvan said less than 15 minutes after Berkin left the house, neighbors arrived saying his son had been wounded.

The boy suffered blunt trauma to the head. According to a report by Human Rights Watch, an eyewitness said the child was hit by a police tear gas canister.

Berkin Elvan has been in a coma in an Istanbul hospital ever since, the family says.

At least four demonstrators and a police officer have been killed in the unrest since May. Thousands of people have been injured. Security forces have detained hundreds of people as part of a broader government crackdown on organizers of the protests.

On Wednesday evening, the Elvan family had not had a chance to begin their speech when police commanders issued three verbal warnings via megaphone for the demonstrators to disperse.

Then they advanced with riot shields, pushing demonstrators out of the square.

In the ensuing melee, CNN journalists witnessed riot police kicking and striking demonstrators with batons. A police officer also fired plastic pellets at demonstrators from the turret of an armored police vehicle that chased protesters down Istanbul's touristic Istiklal Street. On side alleys, squads of riot police pursued demonstrators.

Security forces also sprayed a chemical mist to disperse demonstrators. The burning substance was sprayed over CNN reporter Ivan Watson as he was reporting from the scene of the intervention. More than hour after being hit by the spray, Watson's eyes, nostrils and skin were still burning as a result of the chemicals.

An hour later, at the hospital where his son still lies unconscious in a medically-induced, Berkin's father told CNN he was shocked that the police had not let him speak.

"We just want our child to rejoin us. We are ordinary citizens and our child is sleeping," Elvan said.

As of late Wednesday, CNN had received no response from city government and police officials about the incident earlier in the day. The father of Berkin Elvan says Turkish government officials have not communicated with him about his son's injuries since he was hospitalized June 16.

Prime Minister Recep Tayyip Erdogan has promised to launch an investigation into allegations of excess use of police force since May. But he also has routinely denounced anti-government demonstrators since the protests first erupted -- at various times calling them rodents, riffraff and even claiming they are linked to terrorist organizations.