BERLIN/PRAGUE (Reuters) – Strong winds battered northern and central Europe on Sunday, killing at least six people in Germany, Poland and the Czech Republic, with authorities watching for oil leaks from a huge freighter that ran aground in the North Sea.

Four victims in Poland and the Czech Republic were killed by falling trees. The storm also knocked out power to thousands of Czechs and Poles, and rail traffic in large parts of northern Germany remained suspended after heavy damage from fallen trees.

Winds reached more than 100 kph (60 miles per hour) in several parts of the Czech Republic and topped out at 180 kph on Snezka, at 1,602 meters the country’s highest mountain, Czech Television reported.

The two victims in Germany included a 63-year-old German man who drowned at a campsite in Lower Saxony as a result of a storm surge, and a woman whose motorboat overturned in the state of Mecklenburg-Vorpommern, German media reported.

The “Glory Amsterdam,” a 225-metre long freighter ran aground on the German island of Langeoog, and authorities were keeping a close watch for any signs of oil leaks. The ship’s crew of 22 were safe, the Frankfurter Allgemeine Zeitung reported.

The freighter was not carrying any cargo, but had 1,800 tonnes of heavy oil and 140 tonnes of marine diesel on board as fuel, it quoted local authorities as saying.

In Germany, railway operator Deutsche Bahn [DBN.UL] cited what it called “significant damage” on key routes, and said rail traffic on many routes in northern and central Germany would remain suspended until Monday.

The decision left thousands of travelers stranded and cut rail access to cities such as Bremen, Hamburg, Berlin, Hanover and Kiel. Deutsche Bahn restored some service late on Sunday and provided sleeping cars at stations for stranded passengers.

Hamburg saw widespread flooding in the inner city area, including the area around the new Elbphilharmonie symphony hall.

The winds felled trees in the Czech Republic, with one man dying after being hit on a sidewalk in a town in the north of the country and one woman killed by a tree in a wooded area, media reported.

The weather delayed or halted traffic on several railway lines and slowed road traffic, with a fallen tree blocking one highway just outside of the capital, Prague, the website of newspaper Mlada Fronta Dnes reported.

Prague Zoo closed because of the winds, but Prague Airport was running without problems, newspaper Lidove Noviny’s website reported.

The winds also hit Poland, damaging a pipeline at Poland’s liquefied natural gas terminal in the port of Swinoujscie. They caused a small leak but no greater damage, according to a spokesman for the state gas pipeline operator, Gaz-System.