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At least 31 people — mostly young children — drowned Wednesday after falling from a packed migrant boat while trying to reach Europe from North Africa, rescuers said.

The vessel, one of a group off the Libya coast, listed suddenly, sending about 200 occupants tumbling into the Mediterranean Sea, Italian Coast Guard commander Cosimo Nicastro told Reuters.

"At least 20 dead bodies were spotted in the water," he said.

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Rescue group Migrant Offshore Aid Station (MOAS) said it had recovered 31 bodies. "Most are toddlers," the group's co-founder Chris Catrambone said on Twitter.

No morgue onboard Phoenix. Bodies are being placed on the port side bow. Very sad pic.twitter.com/j1OFfOwxVo — Chris Catrambone (@cpcatrambone) May 24, 2017

The coast guard called in more ships to help with the rescue, saying about 1,700 migrants were packed into about 15 vessels.

More than 1,300 people have died already this year on the most dangerous route for migrants fleeing towards Europe from poverty and war across Africa and the Middle East

Despite efforts by Italy and other European Union nations to bolster Libya's coastal patrols, record numbers of migrants are coming this year.

Crew on the Migrant Offshore Aid Station (MOAS) vessel 'Phoenix' help a man bound for Italy, Wednesday. Chris McGrath / Getty Images

More than 50,000 have been rescued at sea and brought to Italy so far in 2017, a 46 percent increase on the same period of last year, Italy's Interior Ministry said this week.

Most rescues take place just outside the 12-mile marker that separates Libyan territory from international waters.

It is a busy stretch of sea where humanitarian vessels, the Libyan Coast Guard and even scavengers hoping to recover abandoned migrant boats and their engines all operate.