A day of reckoning arrived for BP on Thursday as the oil giant agreed to plead guilty to a raft of criminal charges and pay a record $4.5 billion in a settlement with the government over the deadly 2010 disaster in the Gulf of Mexico. Three BP employees were also charged, two of them with manslaughter.

The settlement and the indictments came 2½ years after the drilling-rig explosion that killed 11 workers and set off the biggest offshore oil spill in U.S. history.

The settlement includes nearly $1.3 billion in fines — the biggest criminal penalty in U.S. history — along with payments to entities inside and outside government. As part of the deal, the BP will plead guilty to charges related to the deaths of the 11 workers and to lying to Congress.

"We believe this resolution is in the best interest of BP and its shareholders," said Carl-Henric Svanberg, BP chairman. "It removes two significant legal risks and allows us to vigorously defend the company against the remaining civil claims."

Also, BP rig workers Robert Kaluza and Donald Vidrine were indicted on federal charges of manslaughter and involuntary manslaughters, accused of repeatedly disregarding abnormal high-pressure readings that should have been glaring indications of trouble just before the blowout.