The crew on a Bangladeshi cargo ship stranded near the Ukrainian port of Olvia heard an explosion, then the bridge was engulfed in flames.

A missile struck the MV Banglar Samriddhi at 5:25 p.m. last Wednesday, killing one crew member and leaving several others with serious burns, according to Bangladeshi crew members, their families and Ukrainian authorities. It was the fifth merchant ship to be hit by artillery off Ukraine’s coast since Russia invaded.

The war in Ukraine has severely hobbled shipping in the Black Sea, with broad consequences for international transport and global supply chains. Dozens of cargo ships are stranded at the Ukrainian port of Mykolaiv, shipping trackers said. An estimated 3,500 sailors have been stuck on some 200 ships at Ukrainian ports, according to London-based shipping tracker Windward Ltd. More ships are stranded around the globe than at any point since World War II, maritime historians said.

The result is a shutdown of the world’s second-largest grain exporting region. Ukraine accounts for 16% of global corn exports, and together with Russia, 30% of wheat exports. Global wheat prices have jumped more than 55% since the week before the invasion.

“This shock to global grain supply is the biggest supply shock since the OPEC oil cuts in the 1970s,” said Salvatore Mercogliano, a professor at Campbell University in North Carolina and former merchant mariner. “It will mean food shortages in the Middle East and Africa, and inflation across the world.”

Making matters worse for global shippers, thousands of Ukrainian and Russian seafarers are stuck in ports around the world, leaving shipowners scrambling to find replacement crews to keep strained supply chains rolling.

In the Black Sea and the adjoining Sea of Azov, which are important food and oil export routes, five tankers and cargo ships have been struck by missiles, according to Ukrainian port authorities. The stricken vessels include tankers, container ships and bulk carriers from Japan, Turkey, Moldova and Estonia, ferrying cargoes including diesel, clay, and grain.

THE CREW OF THE BANGLAR SAMRIDDHI WORKS TO EXTINGUISH A FIRE AFTER THE VESSEL WAS HIT BY A MISSILE.

Ukrainian authorities generally blame Russia, which has amassed a flotilla of warships along Ukraine’s coast. Russia has denied responsibility for the attacks. Russian forces have been targeting missiles at infrastructure in Ukrainian ports—part of a plan to seize Ukraine’s southern coast to cut it off from the sea and suffocate its economy.

On Thursday, an Estonian cargo ship, MV Helt, sank after being hit below the waterline, the vessel’s owner said. Ukraine’s navy has accused Russia of forcing commercial ships to move into a dangerous area of the Black Sea to conceal their own military maneuvers. “Russians [used] the Helt ship as a shield to hide behind it from Ukrainian antiship weapons,” Ukraine’s State Border Guard Service said on Facebook.

Russian forces also have detained two Ukrainian merchant ships, Ukraine’s port authority said.

Ukraine’s paltry fleet is no match for Russia’s naval forces. The Ukrainian navy lost most of its ships when Russia seized its naval headquarters during the 2014 annexation of Crimea. Last week, the navy scuttled its only frigate in Mykolaiv to avoid it being captured by the Russian navy, Ukrainian defense minister Oleksii Reznikov said.

The North Atlantic Treaty Organization warned on Thursday that there is a high risk of collateral damage for any ships in the Black Sea. The International Maritime Organization said on Friday that it would hold an emergency session on March 10 and 11 to address the war’s impact on shipping following requests from numerous governments.

The last NATO naval vessel left the Black Sea about a month before the invasion. Moscow has warned NATO to stay out of waters it claims as its own.

The International Transport Workers’ Federation has declared the waters off Ukraine a “warlike area” and called for further protections for sailors. Advocacy groups for seafarers said many stranded crews are running low on provisions and fuel.