"Fifteen people died from the storm, including 10 in Moscow and five in the Moscow region," the Investigative Committee, a powerful state panel which probes major events, said.
"The dead are of various ages, and include minors," it said in a statement, adding that a hospital in Moscow was operating on two small children who received head injuries.
Late Monday authorities said 13 people had died, mostly due to injuries from falling trees, fences, bus stops and roof covering.
Most people did not receive any sort of warning, normally sent via text messages to cellphones by the emergency ministry. Many were outside, including in parks, when the storm hit.
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"Where was the warning?" wrote Facebook user Dmitry Linter, posting photos of uprooted trees on a street.
"I was walking and was nearly hit by a tree. There are six squashed cars in my courtyard, a couple of smashed windows and a broken lamp post."
Asked about the insufficient warning, Kremlin spokesman Dmitry Peskov on Tuesday told journalists that the nature of the storm may have made it hard to forecast.
Russian weather service on Tuesday said the storm could hit parts of central Russia next and urged people to secure loose objects and be careful about where they parked their cars.