Bild: France Possible Prelude to Wave of Attacks in Europe

The bloodshed in France could signal the start of a wave of attacks in Europe, according to communications by Islamic State leaders intercepted by U.S. intelligence, German newspaper Bild reported Sunday.

Shortly after the attacks in Paris, the U.S. National Security Agency had intercepted communications in which leaders of the jihadist group announced the next wave of attacks, the tabloid said, citing unnamed sources in the U.S. intelligence services.

Paris was cited as being the signal for a series of attacks on other European cities, including Rome, the newspaper said, adding however that a concrete plan of attack was not known.

The U.S. services also had information that Cherif and Said Kouachi, the brothers who carried out the massacre at French satirical weekly Charlie Hebdo, had contacts in the Netherlands, Bild said.

Seventeen people were killed in the attacks on the magazine, a kosher supermarket in Paris and police. The three gunmen -- the Kouachi brothers and Amedy Coulibaly -- were killed by French police.