Interior Minister Carlos Moran said at a news conference before Garcia died that the former president had told police he needed to call his lawyer after they arrived at his home in Lima to arrest him.
Mr Garcia was under investigation in connection with Brazilian construction company Odebrecht, which triggered Latin America's biggest graft scandal when it admitted publicly in 2016 that it won lucrative contracts in the region with bribes.
In November 2018, a judge banned Garcia from leaving the country prompting him to request asylum at the Uruguayan embassy - a request which was denied.
Garcia, who served two terms (1985 to 1990 and from 2006 to 2011) is now under investigation by authorities over bribery claims involving an explosive corruption scandal.
Local TV channel America reported Garcia was undergoing emergency surgery and was in critical condition.
"Alan Garcia has died, long live Apra", said Omar Quesada, the general secretary of Garcia's American Popular Revolutionary Alliance (Apra) party.
Authorities say Odebrecht officials shipped cash across the globe-from one shell bank account to the next-en route to politicians' pockets in a dozen countries, including Peru, Mexico, Venezuela, Colombia, Argentina, and Mozambique.
Toledo, 73, is now in the United States. He continued to deny any wrongdoing in the Odebrecht scandal.
Kuczynski was urgently taken to hospital on Wednesday suffering from high blood pressure, lawmaker Gilbert Violeta said.
Ecuador suspended Vice President Jorge Glas, who was later sentenced to six years in prison in December 2017 for receiving $13.5 million in bribes from Odebrecht.
Garcia had been about to be arrested over corruption claims after allegedly taking illegal payments from Odebrecht, a Brazilian construction giant.
Alan Garcia is not the only former Peruvian president whose name is linked to the firm and who is being suspected of being involved in corrupt schemes.
While three former presidents in Peru have also been ordered to jail in connection with Odebrecht, Garcia had blamed his legal troubles on political persecution, accusing President Martin Vizcarra without evidence of trying to silence him. A hearing is scheduled to take place Wednesday to decide whether to increase his detention to three years.