MIDDLETOWN, Conn. -- Enough natural gas to fill a professional basketball arena was vented into tight quarters shortly before an explosion at a Connecticut power plant that killed six workers, a federal safety investigator said Thursday.

Donald Holmstrom, of the U.S. Chemical Safety Board, said the practice of cleaning pipes at the under-construction power plant, known as a "gas blow," put 400,000 cubic feet of gas into an area close to the plant's power block, and near many ignition sources.

MIDDLETOWN - Close to 400,000 cubic feet of gas was released into the atmosphere behind the Kleen Energy building in the final 10 minutes before the explosion that killed six and injured 27, the lead investigator of the Chemical Review Safety Board said today.

Donald Holmstrom, lead investigator of the Chemical Review Safety Board, said that the gas was released into a congested area next to the power block building, and that the congested area likely slowed the dispersion of the gas and was ignited by an undetermined ignition source. The gas released was enough to fill a basketball arena, Holmstrom said.

LOS ANGELES (Reuters) - More than 31 million Americans watched Michael Jackson's public memorial on television, but mystery surrounded the whereabouts of his body on Wednesday and plans for his burial.

A day after Jackson's casket was taken to a Los Angeles basketball arena for an emotional memorial for fans, friends and his family, attention returned to how Jackson got his hands on powerful prescription drugs reportedly found in his rented mansion after his sudden death on June 25.

LOS ANGELES (Reuters) - Los Angeles city officials are planning a massive security operation for Michael Jackson's public memorial service next week, and on Friday urged fans who do not win a ticket in a random drawing to stay away from the basketball arena where the singer will be memorialized.

Organizers have set aside a total of 17,500 tickets through an Internet-based lottery for the televised service at the Staples Center, and for a closed-circuit screening at the nearby Nokia Theater.

â??Amid a scattering of angry protests over his support for abortion rights, President Obama addressed the issue head-on Sunday at the University of Notre Dame, calling for â??open hearts, open minds, fair-minded wordsâ?? in the pursuit of â??common ground,â??â? the Washington Post says. More: â??The vast majority of the 12,000 in attendance at the Joyce Center basketball arena gave the president several loud, sustained ovations, and the crowd rallied to his defense when people attempted to interrupt him at the start.

SOUTH BEND, Ind. -- Confronting the nation's deep schism over abortion, President Barack Obama on Sunday called for greater understanding on all sides as he spoke to graduates and others at one of America's premier Catholic universities.

Obama stressed the importance of common ground as opponents of abortion rights protested his appearance and the honorary degree he received from the University of Notre Dame.