Yitzhak Gross, who has been hospitalized in critical condition since his exposure to deadly pesticide that killed his two younger sisters, regained consciousness and began breathing on his own, the Schneider Children’s Medical Center announced Wednesday.

The 5-year-old boy spoke with his parents and ate a lollipop.

His elder brother, Michael, 7, remains sedated. However, on Tuesday doctors disconnected the ECMO respiration and cardiovascular machines, as Michael’s heart and lungs began functioning autonomously.

“It’s difficult to say whether Yitzhak’s life is out of danger, but there is no doubt that this is great progress and a significant improvement,” Dr. Ovdi Dagan, director of the Cardiac Intensive Care Unit, said, according to Ynet. “He is still receiving medication for his heart, but he is conscious and communicating.”

Dagan said that the doctors were “pleasantly surprised” by the boy’s progress, as studies on phosphine inhalation have shown that in the best cases it generally takes two weeks for a patient to wake up. There is no known antidote to the poison.

“We still don’t know when we will be able to wake Michael up,” Dagan said.

Yitzhak opened his eyes on Saturday for the first time, and doctors reported that the conditions of the two boys had significantly improved.

The boys’ parents thanked the public for their prayers and support, and asked them to continue to pray for a full recovery.

The family fell ill after an exterminator allegedly used aluminum phosphide during a visit to the family’s home in the Givat Mordechai neighborhood of Jerusalem last Monday. When mixed with water, the toxin reacts to release phosphine, an extremely harmful gas.

Avigail and Yael, aged 1 and 4, were rushed to the hospital last Wednesday along with the rest of their family, but doctors were unable to save their lives. The girls were laid to rest on Thursday at Jerusalem’s Har Hamenuhot cemetery.

The exterminator suspected of negligence in the girls’ death reportedly left a container of the poisonous material inside a room that he sealed with masking tape, intending to return to continue his work.

Times of Israel staff contributed to this report