MOSCOW -- Russia's coast guard opened fire on and seized three of Ukraine's vessels Sunday, wounding two crew members, after a tense standoff in the Black Sea near the Crimean Peninsula, the Ukrainian navy said.

Russia blamed Ukraine for provoking the incident, which sharply escalated tensions that have been growing between the two countries since Moscow annexed Crimea from Ukraine in 2014, and it has worked steadily to bolster its zone of control around the peninsula.

Earlier in the day, Russia and Ukraine traded accusations over a separate incident involving the same vessels, prompting Moscow to block passage through the narrow Kerch Strait, which separates the peninsula from the Russian mainland.

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The Ukrainian navy said two of its gunboats were struck and Russian crews boarded and seized them and an accompanying tugboat.

Russia's Federal Security Service, known as the FSB and which oversees the coast guard, said there was "irrefutable evidence that Kiev prepared and orchestrated provocations ... in the Black Sea. These materials will soon be made public."

The FSB confirmed early Monday that it fired on the vessels to force them to stop, and then seized them. Russia claims the Ukrainian vessels were violating it's territorial waters.

As CBS News correspondent Elizabeth Palmer reports, the facts of the matter remain unclear, but the U.S. appears to be agreeing with the Ukrainians. U.S. government special envoy on Ukraine Kurt Volker tweeted early Monday that Russia had rammed the Ukrainian tugboat as it was "peacefully travelling toward port...and then accuses Ukraine of provocation????"

Russia rams Ukrainian vessel peacefully traveling toward a Ukrainian port. Russia seizes ships and crew and then accuses Ukraine of provocation??? — Kurt Volker (@SpecRepUkraine) November 26, 2018

An emergency meeting of the United Nations Security Council was called for Monday morning over the escalating situation, which would be attended by outgoing U.S. Ambassador Nikki Haley.

CBS News' Pamela Falk said the emergency meeting was called by the Russian Mission to the U.N.'s Deputy Ambassador Dmitry Polyanskiy. He said he had called the meeting, "to discuss dangerous Ukraine provocations in the sea of Azov and Kerch Strait near Crimea threatening international peace and security."

Ukraine's Ambassador to the global body, Volodymyr Yelchenko, fired back in a tweet, however, referring to "the audacious behavior of the aggressor," which he said could only be addressed "by joint coordinated efforts."

The European Union and NATO called for restraint from both sides and for Moscow to restore access to the strait, which Ukraine uses to move ships to and from ports on either side of the peninsula.

Ukrainian authorities said they had given advance notice to the Russians that the vessels would be moving through the strait, which connects the Black Sea to the Sea of Azov.

Russia said the three Ukrainian vessels made an unauthorized passage through Russian territorial waters, while Ukraine alleged that one of its boats was rammed by a Russian coast guard vessel.

The tugboat which was rammed was traveling with the two Ukrainian gunboats from Odessa on the Black Sea to Mariupol, an eastern Ukraine port, via the Kerch Strait.

"Russian coast guard vessels ... carried out openly aggressive actions against Ukrainian navy ships," the Ukrainian statement said, with the tugboat suffering damage to its engine, hull, side railing and a lifeboat.

МВС України спецзасобами отримало доступ до відео провокації -тарана російського прикордонного корабля "Дон" українського🇺🇦 судна. Перехоплене відео знято російськими, чутні команди - це піде доказом в міжнародний суд!

Агресія! Гуртуемось та очікуємо реакції дружніх країн! pic.twitter.com/f0e9hFB1BT — Arsen Avakov (@AvakovArsen) November 25, 2018

Ukraine's Interior Minister Arsen Avakov posted a video to Twitter on Sunday which was apparently shot from inside the Russian vessel as it rammed the Ukrainian tug. Avakov did not reveal how the Interior Ministry obtained the video, but in it a Russian officer can be heard giving orders to his crew to continue steaming toward the much smaller vessel to force it off course. After the impact with the tug he orders his crew to stop their own vessel.

Avakov called the 1 minute and 15 second video proof of Russian "aggression" and said he was looking forward to receiving support from Ukraine's allies in response.

Russia blocks key sea passage

The Kerch Strait is the only passage into the Sea of Azov. The strait is spanned by the recently completed and highly symbolic Kerch Bridge, connecting Crimea to Russia. Transit under the bridge has been blocked by a tanker ship, and dozens of cargo ships awaiting passage are stuck.

Russia has not given any indication of how long it will block the strait, but a long-term closure to would amount to an economic blockade of Ukrainian cities on the Azov coast. Russia's Black Sea Fleet greatly outmatches the Ukrainian navy.

Ukrainian ports on the Sea of Azov include strategically vital centers such as Mariupol, the closest government-controlled city to Donetsk and Luhansk, the breakaway regions of eastern Ukraine controlled by Russia-backed separatists. Thousands of people in those regions have been killed in fighting between Ukrainian troops and the separatists since 2014.

Ukraine blames Russia, Russia blames Ukraine and U.S.

The FSB told Russian news agencies after the first incident that the Ukrainian ships held their course and violated Russian territorial waters.

"Their goal is clear -- to create a conflict situation in the region," the FSB statement said. It did not mention that a Ukrainian tugboat was rammed.

Although a 2003 treaty designates the Kerch Strait and Sea of Azov as shared territorial waters, Russia has been asserting greater control over the passage since 2015.

The Ukrainian Foreign Ministry said earlier that Russia's actions violated the U.N. Charter and international law, and pledged to "promptly inform our partners about Russia's aggressive actions."

"Such actions pose a threat to the security of all states in the Black Sea region," the statement said, "and therefore require a clear response from the international community."

Ukrainian President Petro Poroshenko, after a meeting with his National Security Council, said in a statement he would ask parliament Monday to take up the issue of whether to implement martial law over the incident. Palmer notes that under martial law, Poroshenko would be able to more quickly mobilize his own military for an escalation with Russia.

Many of his opponents, however, point to the fact that he is also calling for martial law -- for the first time during years of tension with Russia -- about a month before campaigning is due to begin for presidential elections in March. An official declaration of marital law would force the campaigning, and possibly the election, to be delayed.

About 50-100 people gathered outside the Russian Embassy in Kiev to protest Moscow's actions.

Dmitry Kiselyov, a commentator on Russian state-controlled TV, told viewers of his Sunday evening news program that Poroshenko, encouraged by the U.S., is looking to pick a fight with Russia in the Black Sea.

The talk show host also alleged the U.S. talked Poroshenko into staging a provocation against Russia as a means to disrupt an upcoming meeting between Presidents Vladimir Putin and Donald Trump at this week's Group of 20 summit in Argentina.

"What is happening now at the (Kerch) bridge threatens to turn into a very unpleasant story," Kiselyov said.