Former Israeli President Shimon Peres suffered a massive stroke Tuesday and is in critical condition, the Jerusalem Post reported.

Peres, 93, underwent surgery last week to have a pacemaker implanted and was released the following day in good condition.

Communications consultant Ayelet Frish said Peres woke with palpitations and a constricted feeling in his chest. He also had difficulty breathing, Frish said. He was taken to Sheba Medical Center at Tel Hashomer for tests.

He fell ill while working on a video urging Israelis to buy Israeli products, the New York Times reported.

It was unclear whether the pacemaker was connected to the stroke or what type of stroke occurred. Peres’ son, Hemi, asked people to pray for his father.

“These hours are not easy for me and my family. My father underwent a difficult ordeal and I want to first and foremost thank the medical staff who is examining him and consulting with the family. We will have to make difficult decisions, but not at this moment,” he told reporters according to Arutz Sheva.

Israeli Prime Minister Benjamin Netanyahu wished Peres a speedy recovery.

The Post said Peres was admitted in stable condition but it then worsened. His office said he had been placed on a respirator.

“Peres underwent several tests and is being treated by the best doctors. In the coming hours, we will assess his condition,” hospital director Itzik Kreis said.

Peres was born in Wiszniewo, Poland, and was among the founders of the Labor-Zionist Youth Movement. He also was a member of the Haganah before Israel became a state in 1948. At the age of 29 he became the director general of the Defense Ministry and joined the Knesset in 1959.

The New York Times characterized Peres as an important figure in developing Israel’s military, including its nuclear program. He served as prime minister twice, shared a Nobel Peace Prize with Yitzhak Rabin and Yasser Arafat, and served as president from 2007 to 2014.

Hemi Peres said his father was devoted to Israel.

 “Nothing is more precious to my father than the nation of Israel and its people. My father is a special person and I am remaining optimistic. I am praying and hoping for the best,” he said.