THE HAGUE, Netherlands (AP) — Ride hailing firm Uber is raising the minimum age of its drivers in the Netherlands and taking other measures to increase road safety after a recent series of fatal accidents involving Uber drivers.

Uber Nederland General Manager Thijs Emondts says in a statement Monday that the company is lifting the minimum age of drivers from 18 to 21 years.

Uber also will insist that drivers have at least one year's driving experience and will develop a mandatory traffic safety training course for all drivers under the age of 25.

Rob Stomphorst, a spokesman for road safety organization Safe Traffic the Netherlands, says four people have died in recent weeks in crashes involving Dutch Uber cars. He says the circumstances of the crashes remain under investigation.

Uber's Dutch arm did not immediately return calls seeking comment.