Two undetonated explosive devices were found Thursday attached to a ferry at a popular Mexican tourist destination where several Americans were injured in a separate explosion last month.

Mexican officials said they are investigating the explosive founds in the ferry that runs between Playa del Carmen and Cozumel, while the U.S. embassy in Mexico issued a security alert.

"U.S. government employees are prohibited from using all tourist ferries on this route until further notice. Mexican and U.S. law enforcement continue to investigate," the embassy said in the alert.

7 AMERICANS AMONG INJURED AFTER FERRY EXPLOSION IN MEXICO

Last month’s blast aboard a ferry on the same route injured 25 people, including seven Americans. None of the injuries were life-threatening. The ferry was unloading passengers in Playa del Carmen on Feb. 21 when the explosion occurred.

Quintana Roo port officials said at the time that it appeared a mechanical failure was to blame. However, the U.S. embassy said Thursday the blast was due to an explosive device.

Except for isolated shootings last year, the Caribbean coast had largely been spared the violence plaguing other parts of Mexico. The coast provides much of Mexico's tourism revenue.

The company whose boat was hit by the Feb. 21 blast was suspended from operating four days later. The firm said it had the necessary operating permits.

Local media have reported the company is owned by the father of former Quintana Roo state governor Roberto Borge, who is under arrest on corruption charges.

Local media have also reported that a drug gang had taken credit for the blast, Reuters reported.

The Associated Press contributed to this report.