Two suspected human smugglers were arrested in Italy this week after the bodies of 26 Nigerian women and girls, all of them believed to be teenagers, were found dead on the Mediterranean Sea.

The Guardian reports that the two suspected smugglers, identified as Al Mabrouc Wisam Harar from Libya and Mohamed Ali Al Bouzid from Egypt, are accused of trafficking at least 150 people, but prosecutors have not directly linked them to the deaths.

It is still unclear exactly how the women and girls died, but autopsy results are expected soon.

Investigators suspect that the women and girls, some as young as 14, may have been murdered while attempting the dangerous smuggling route between Libya and Europe. The bodies were reportedly discovered by an anti-trafficking rescue boat called the Cantabria at the site of two separate shipwrecks.

By the time aid workers arrived, survivors were clinging to the mostly sunken remains of a rubber dinghy while deceased floated nearby, an Italian police official told CNN. The recovered bodies were brought to shore Sunday in Salerno, Southern Italy, along with an unknown number of survivors who were among almost 400 migrants rescued in recent days.

Read more: ‘This is Hell on Earth.’ Eyewitness to a Harrowing Rescue on the Mediterranean

While deaths are common along the migrant sea route to Europe, it is unclear why the victims from this crossing all appear to be young women. Salerno police chief Lorena Ciccotti told CNN that investigators were still trying to determine if the girls had been tortured or sexually abused.

More than 150,000 migrants and refugees have survived the journey over the Mediterranean Sea and entered Europe this year as of Nov. 1, according to the International Organization for Migration. Most, or about 75%, have arrived in Italy, with the rest ending up in Greece, Cyprus or Spain. More than 2,800 people have died while attempting the crossing this year, down from 4,150 in 2016.

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Write to Laignee Barron at Laignee.Barron@time.com.