TRAPANI, Italy _ As darkness fell, the rescue ship Vos Hestia sailed south of Sicily, searching for stranded migrants in the world's deadliest sea crossing.
By 10:30 p.m., Italian officials were radioing reports of a smugglers' boat, then a second and a third, packed with hundreds of migrants.
Vos Hestia's captain responded that his ship would try to save the larger vessel.
Named for the goddess of family, the Vos Hestia is run by the London-based nonprofit Save the Children. It's equipped with a clinic, latrines and wash basins, and can feed and sleep hundreds on deck. But the crew had never saved more than 400 migrants at once, and never at night, which was considered especially risky.
Roger Alonso, the rescue team leader, checked the ship's radar. Then he stepped outside the bridge to scan the waves.
"We see it on the radar, but ... " he said.
Suddenly, the captain started shouting:
"Roger, Roger, you see the light?"
Screams woke him after the smugglers' boat left the Libyan coast.
The slender 15-year-old Eritrean had boarded the 40-foot blue double-decker wooden boat on a beach in Sabratha, about 50 miles west of Tripoli. But now the youth _ who asked to be identified by his initials, M.Y., to protect his family from persecution _ worried he might not live to see Europe.
The teenager had been herded below deck with 200 other migrants, half younger than 18. Like M.Y., most were traveling without their parents.
About 200 others were seated above deck, mostly women, children and Moroccans who paid more for their passage.
The scream had come from another Eritrean, a man with a broken leg jostled by the crush of people. The motor belched fumes, the temperature climbed and M.Y. could smell vomit and human waste descending from above. The youth feared that he might suffocate as he and other migrants gasped for air from slits in the boat's sides.
Three smugglers had accompanied them, armed with Kalashnikovs, bayonets and night vision goggles. Several miles off shore, the smugglers climbed aboard another boat, intending to linger nearby to retrieve the first vessel after the migrants were rescued.
Some migrants became alarmed at being abandoned and abruptly stood up, rocking the boat. Water streamed below deck.
The smugglers had given one of the migrants, a Sudanese man, their satellite phone to alert authorities. The man tried to restore calm. He warned those above to sit and those below to stay down and to cover the screaming man's mouth. They did.
M.Y. felt water seeping in around him. The motor strained to pump it out. He prayed he would survive.
Then came updates from above: There was a light ahead. Some said it was Malta, others Italy. The Eritrean youth worried that it was Libyan authorities or militias that might send them back _ or worse, seize the boat and dump them in the sea.
The light soon revealed the shape of a ship _ the Vos Hestia. M.Y.'s heart leapt as those above shouted, "A rescue team is coming!"
The Sudanese man, Azhri Alshreef, had used the satellite phone to call Italian maritime officials.
Then he dialed his father in Khartoum.
"I'm here, I got on," Alshreef said as the Vos Hestia's floodlight approached.
"Thank God you are safe," his father said.
Alshreef, 31, threw the phone in the ocean, as the smugglers had instructed, to avoid being mistaken for one of them.
The migrants' trip had lasted four hours.
