Oil giant BP’s chief operating officer says the company’s main strategy for containing a massive oil spill in the Gulf of Mexico has not worked.

But Doug Suttles says the company will continue to seek a way to successfully cover a leaking oil well with a huge dome. Ice-like crystals clogged the device while engineers lowered it deep underwater.

Beachgoers found balls of tar on an island (Dauphin Island) off the coast of southern Alabama Saturday. Testing is underway to see if the tar balls are from the spill. Oil also has reached a wildlife reserve (on the Chandeleur Islands) off southern Louisiana’s coast.

Among BP’s other efforts to contain the flow of hundreds of thousands of liters of crude per day, the company is drilling a relief well to pump the leaking reservoir. But BP says the well will take about three months to complete.

The spill began after an oil rig exploded on April 20 and killed 11 workers in the Gulf of Mexico.

Survivors say the blast’s apparent cause was a huge bubble of methane gas that traveled up the rig’s drilling pipe and caught fire at the top. A series of major explosions followed, bringing down the rig.

(Sources: AP, AFP and Reuters)