Russia fired on three Ukrainian ships in the Black Sea on Sunday, injuring at least two crew members, and then seized the vessels, Ukraine said — as tensions between the two countries reached a near-boiling point.

Ukrainian President Petro Poroshenko called an emergency meeting of his war cabinet in response to the incident, according to The Guardian UK.

There has been growing unease in the region as Russia has steadily worked to increase its zone of control around Crimea, which it annexed in 2014.

But hostilities escalated Sunday when Russia prevented three Ukrainian vessels from passing beneath a Russian-controlled bridge in the Kerch Strait, which connects the Sea of Azov to the Black Sea.

Two artillery ships and a tug boat were subsequently fired on and seized, the Ukranian navy said.

But the Russian Federal Security Service, Russia’s principal security agency, said there was “irrefutable evidence that Kiev prepared and orchestrated provocations” — vowing to make more information about the incident public.

Earlier in the day, the Ukrainian navy said Russia’s coast guards had rammed one of its tugboats in the Black Sea off of Crimea in what it perceived as an “openly aggressive action.”

The statement from Ukraine said Russia had been informed in advance about the tugboat’s planned journey.