Venezuelan President Hugo Chavez died Tuesday afternoon after a long battle with cancer, Vice President Nicolas Maduro said.
Flanked by Cabinet ministers, Maduro teared up as he announced the news in a national broadcast.
"We must unite now more than ever," he said, calling on Venezuelans to remain peaceful and respectful.
In the coming hours, Maduro said, plans for Chavez's funeral would be announced.
Maduro said Chavez died Tuesday at 4:25 p.m. (3:55 p.m. ET). He did not specify when elections would be held, or who would run the country in the meantime.
"Our people can count on having a government of men and women committed to protecting them," Maduro said.
The announcement came hours after Maduro met with the country's top political and military leaders about Chavez's worsening health condition and suggested someone may have deliberately infected Chavez with cancer.
Venezuela's defense minister echoed Maduro's calls for unity and peace.
Adm. Diego Molero said Venezuela's military is in a "process of deploying ... to ensure the safety of all Venezuelans" and to support the country's constitution in the wake of Chavez's death.
Molero pledged support to Maduro and National Assembly President Diosdado Cabello, two top officials who were close allies of the Venezuelan president.
Chavez first announced his cancer diagnosis in June 2011, but the government never revealed details about his prognosis or specified what kind of cancer he had.
He died nearly three months after his last public appearance.
The president was known for his frequent television broadcasts and lengthy speeches.
Shortly before his last trip to Cuba for cancer surgery in December, Chavez tapped Maduro as the man he wanted to replace him.
"He is one of the young leaders with the greatest ability to continue, if I cannot," Chavez said.
Maduro made no mention of running for election in his public comments Tuesday, but he is widely expected to be the United Socialist Party of Venezuela's candidate for the job.
After the announcement of Chavez's death, state-run VTV showed images of people in the streets of Caracas crying and carrying posters with the late president's picture.
Word of Chavez's death drew swift expressions of sorrow and solidarity from regional allies.
"The national government expresses its solidarity in light of this irreparable loss that puts the Venezuelan people and all the region in mourning and at the same time sends its heartfelt condolences to the family of the late champion of Latin America," Ecuador's foreign ministry said in a statement.
Bolivian President Evo Morales' voice cracked as he spoke to reporters, describing Chavez as someone "who gave all his life for the liberation of the Venezuelan people ... of all the anti-imperialists and anti-capitalists of the world."
But longtime critics of the controversial president offered a different take.
"Hugo Chavez was a destabilizing force in Latin America, and an obstacle to progress in the region," said U.S. Rep. Mike Rogers, the Republican chairman of the House Intelligence Committee. "I hope his death provides an opportunity for a new chapter in U.S.-Venezuelan relations."