Here are the main developments:

What happened?

The President was accused of being unduly influenced by her longtime friend and adviser, Choi Soon-sil, who is on trial for abuse of power and fraud.

The Constitutional Court agreed with accusations that Park had abused her authority in helping Choi raise donations from companies for foundations she had set up.

"We announce the decision as the unanimous opinion of all judges. We dismiss the defendant President Park," said Justice Lee Jung-mi.

An election for Park's replacement must be held within 60 days, and an ad-hoc cabinet meeting will be held soon, a government official told CNN.

Liberal candidate Moon Jae-in, of the opposition Democratic United Party, currently leads the opinion polls. Moon was defeated narrowly by Park in 2012.

Chaos on the streets

Soon after the court's ruling, acting President Hwang Kyo-ahn appealed for unity, acknowledging that the conflict had polarized the nation. South Koreans on opposing sides saw each other as "enemies," he said in a televised address. "Now is the time, however, for acceptance," he said.

As the court's decision was delivered, a group of around 100 Park supporters tried to break through police lines near the court, and a number fell and were injured. "We lost our liberty. We lost our Korea," one protestor told CNN.

Anti-Park demonstrators also took the streets, some crying tears of joy and pumping fists in celebration, as applause rang out from the crowd. Many had camped out in the streets overnight in the cold.

Police had issued the highest level of emergency order possible in Seoul ahead of the announcement. About 21,000 officers were on standby for the protests, with 270 units mobilized.

Fall from grace

Park's election in 2013 as the South Korea's first female president was widely celebrated as a milestone. But her fumbled response to a ferry disaster tainted her rule, and allegations about her relationship to Choi emerged during 2016.

Choi was arrested after being accused of abusing her relationship with the President. She denies claims that she forced companies to donate millions of dollars to foundations she had established.

The case widened to ensnare Lee Jae-yong, the acting head of electronics giant Samsung.

Prosecutors allege that Lee pledged tens of millions of dollars to win favor with Park and secure government support for a merger that helped tighten his grip on the company. He is on trial for charges of bribery and corruption, which he denies.

In December, lawmakers voted to impeach Park by a vote of 234 to 56, stripping away her executive powers. Since then she has remained in the presidential palace, known as the Blue House, but has remained largely out of public view.

Friday's ruling means Park loses the protection from prosecution she enjoyed as president and that she could now face a formal investigation.

Security concerns

Hwang, who became acting President when Park was impeached, warned that North Korea could exploit the political uncertainty.

South Korea's political stability is crucial to the security of the region -- it is a key buttress against North Korea, its provocative neighbor, and a major trading partner with the US and its Asian neighbors.

The US moved quickly to issue a reassuring statement, saying the two countries' relationship would be unaffected.

"We will continue to work with Prime Minister Hwang for the remainder of his tenure as acting President, and we look forward to a productive relationship with whomever the people of South Korea elect to be their next president," acting State Department spokesman Mark Toner said.

North Korea's official news agency noted that Park had lost her immunity, reporting that she would be investigated as a "common criminal."