Police are still investigating what caused half a dozen boats on the eastern Rummelsburger Bay of the Spree River to catch fire early Thursday morning, according to Tagesspiegel.

Emergency services were alerted to the fire at about 4.30am and were able to ultimately put out the flames. Among the boats were two recreational vessels and one house boat.

According to BZ, the cause of the blaze was still unclear later in the morning, but police suspect arson.

Initially fire services encountered a problem in trying to douse the flames because Berlin’s only proper fire extinguishing boat was in Spandau on the other side of the city. On top of that, the fire specialists who could use the right equipment to put out the blaze were attending to an apartment fire in Köpenick, Tagesspiegel reported.

That Berlin has just one proper fire services boat has been a complaint for years.

Fire chief Wilfried Gräfling told the newspaper that adding another fire boat would be too expensive. At one time the city had five, but they became too expensive to maintain.