NEW ORLEANS — Authorities are still searching for a tugboat that sank in the Mississippi River, prompting the closure of a stretch of the river south of New Orleans over the weekend.

The Mississippi from its mouth to mile marker 10 was reopened Sunday night to alternating one-way vessel traffic after no navigation hazards were detected. The Coast Guard said in a news release that it was unclear when the stretch of river would be open to two-way traffic.

Although 15 ships were waiting to travel upriver at one point Monday, Coast Guard Chief Petty Officer Bobby Nash said the queue had been cleared by late morning.

Authorities are still searching for the 48-foot tug C-Pec, which sank Saturday. The cause isn’t known. Two people aboard were rescued.

One cruise ship bound for New Orleans was diverted to Mobile, Ala.