In the early hours of Wednesday, two letter bombs went off in two Dutch cities, local police confirmed.
A parcel exploded in the capital Amsterdam after being received in the mailroom of a company in the northwestern area of the city, at 8.00 a.m. local time (0700 GMT).
None were injured in the attack, Amsterdam police announced on Twitter.
The second blast hit Kerkrade, the southernmost province of Limburg.
“A letter package exploded at a postal sorting company on Wiebachstraat in Kerkrade around 8:30 am [0730 GMT]. No one was hurt,” said the Limburg police on Twitter.
The building was evacuated and police investigations are ongoing, it added.
“It is still unknown whether there is a connection with the explosion of a letter package this morning in Amsterdam,” said the Limburg police.