National Park Service officials are warning that oil from the Deepwater Horizon disaster in the Gulf of Mexico could come ashore on some parts of Gulf Islands National Seashore this weekend.

On April 20, the oil rig drilling platform exploded in the Gulf of Mexico, killing 11 of the 126 people on board. Since then it has spewed millions of gallons of crude oil into the gulf.

By April 25 it was determined that oil was leaking from the well and the National Parks along the Gulf began to prepare for the potential of oil contamination.

While there have been no closures on the seashore related to the accident, crews were working Saturday to remove "two large compressed gas tanks that washed up on Horn Island." Officials did not know if the tanks had come from the Deepwater Horizon.

Meanwhile, park officials said "projections show there is a potential for oil to impact the Mississippi islands over the weekend, but the heaviest concentrations are expected to remain well south of the park during that period."

On Friday, crews continued to monitor resources across the Gulf Islands, and failed to detect any oil along the seashore's shorelines, which run from Mississippi to Florida.

As for the gas tanks that washed up at Horn Island, an NPS criminal investigator dove at the site to document the condition of the seagrass bed before a contractor removed them.

Crews also worked Saturday on boom deployment around Cat Island and Ship Island, and an additional boom was placed off the south side of the island in deeper water to deflect incoming oil, the Park Service said.

Other Gulf coast units of the National Park System that also were preparing to respond to oil in their waters and along their shores included Big Cypress National Preserve, Biscayne National Park, De Soto National Memorial, Dry Tortugas National Park, Everglades National Park, Jean Lafitte National Historical Park and Preserve, and Padre Island National Seashore. Crews at those parks were focused on developing baseline resource assessments that could be used if oil did come ashore or affected the parks' waters.

According to the National Park Service, the following resources are at risk:

* Seagrass beds are important nursery habitat for sea turtles, young fish, crabs, shrimp, and many other crustaceans. They also provide an important food source for manatees. Oil will kill seagrasses on contact and this community is slow to recover.

* Salt marshes, which occur in back bays, provide a buffer that protects the mainland during storm events. They also offer foraging sites for all kinds of birds. If oil kills these plants in the marsh, the soil will destabilize and erode.

* Mangroves are similar to salt marshes in that they provide a buffer between the sea and the mainland, as well as providing wildlife habitat.

* Shipwrecks, archeological sites, Civil War defenses, and other historic structures tell the stories of past inhabitants and key moments in our nation’s past. Damage from oil and cleanup operations is a concern for these treasures.

Federal agencies have drafted a release on how wildlife impacted by oil should be handled. It's attached below.