All eyes were on Seoul's presidential Blue House on Saturday as South Koreans awaited ex-president Park Geun-hye's reaction to her impeachment and preparations to move into her private residence.

Election authorities expressed concern over growing tensions in the lead-up to polls to elect a new president, while newspaper editorials called for an end to ongoing street protests.

A third person died on Saturday in hospital after clashes between pro-Park supporters and riot police, near the Constitutional Court which confirmed Park's impeachment.

A spokesperson for the protesters supporting the court ruling, Choi In-sook, told Reuters news agency they were demanding the arrest of their former leader.

"We demand the arrest of Park Geun-hye and the resignation of acting president Hwang Kyo-ahn," said Choi.

News reports said Park was watching television alone in her private presidential room on Friday when the country's highest court announced her dismissal live on air.

REPORTER'S NOTEBOOK: The day Park Geun-hye was ousted

An incredulous Park immediately phoned her aides to confirm the verdict, the Chosun Ilbo daily said.

Her aides told the newspaper she had no immediate plans to issue a statement on the court decision or her future course of action.

"The president was apparently stunned at the ruling. She looked dejected," an unidentified aide was quoted as saying. "She wants to keep to herself for a while," he added.

Park will leave the Blue House only after her private house in prosperous southern Seoul is repaired and cleaned to accommodate her and her security detail.

TV footage showed materials being unloaded from a small truck parked outside the two-storey house.

Police said more than 200 officers were deployed around the area.

Park is obliged to move out of the presidential palace, where she has been holed up for more than 90 days after the National Assembly voted for her impeachment in October.

READ MORE: The fall of President Park Geun-hye - A day-by-day look

The court's verdict upholding her impeachment immediately stripped her of all powers and privileges, except for her security.

Park was found to have broken the law by allowing her friend Choi Soon-sil to meddle in state affairs, and breached rules on public servants' activities.

The ruling also stripped her of presidential immunity to criminal indictment.

The president's "acts of violating the constitution and law are a betrayal of the public trust", Acting Chief Justice Lee Jung-mi said.

"The benefits of protecting the constitution that can be earned by dismissing the defendant are overwhelmingly big. Hereupon, in a unanimous decision by the court panel, we issue a verdict: We dismiss the defendant, President Park Geun-hye."

Lee accused Park of colluding with Choi to extort tens of millions of dollars from businesses and letting Choi, a private citizen, meddle in state affairs and receive and look at documents with state secrets.

Those allegations were previously made by prosecutors, but Park has refused to undergo any questioning, citing a law that gives a sitting leader immunity from prosecution.

It is not clear when prosecutors will try to interview her.

Journalists attacked

Park has already been named a criminal suspect, accused of bribery for offering policy favours to firms that benefited Choi.

For months, she has refused to make herself available for questioning by prosecutors probing the scandal.

But that may no longer be an option once she leaves the Blue House, when she could face formal arrest if she refuses a summons.

South Korea's top election official Kim Yong-deok said in a statement there was "growing concern" over the highly charged atmosphere before an election which must take place before May 9.

"The vote must serve as a chance to overcome divisions and conflicts and achieve national unity and harmony," he said in a speech aired live on TV across the country.

Police issued a statement vowing to track down and punish unruly protesters as pro-Park supporters planned to hold fresh demonstrations near the Constitutional Court and in the city centre on Saturday afternoon.