"An oil rig exploded on a Louisiana lake Sunday night, injuring seven people, five of them critically, while another person remained unaccounted, authorities said.
The explosion on Lake Pontchartrain was reported at 7:18 p.m. (8:18 p.m. ET) about 1½ miles from shore, authorities said at a briefing late Sunday. Rescue efforts were still underway, they said.
The cause remained unknown, and authorities said it was too soon to tell whether any oil had spilled. Ben Zahn, the mayor of nearby Kenner, said no homes were threatened. "