Energy giant BP will hold a worldwide moment of silence Wednesday for the victims of last week's hostage crisis at an Algerian gas plant, with its CEO saying employees "fear the worst" for four colleagues still missing.

Nearly a week after Islamic militants seized the In Amenas facility in the Sahara Desert, families and governments around the world were waiting for the Algerian government to provide a full accounting of the dead and missing. Algerian authorities say five workers are still missing after its special forces stormed the compound in a bloody weekend raid that left most of the terrorists and their remaining captives dead.

The plant is run by Algeria's state oil company, in cooperation with foreign firms such as Norway's Statoil and Britain's BP. Tuesday night, BP CEO Bob Dudley said four of its 18 employees at the plant remain unaccounted for, and "It is with great sadness that I now have to say that we fear the worst for them all."

The company said its offices worldwide will hold a minute of silence Wednesday "as a mark of respect for all of those who lost their lives at In Amenas."

At least 37 hostages were killed in the four-day ordeal, which began December 16 and ended Saturday.

"Many of us have friends and colleagues, both in BP and in other companies, who have worked at In Amenas or in similar facilities," Dudley said in a company statement. "We are all thinking of our missing colleagues, those who endured the ordeal and their loved ones."

The plant employed about 790 people, including 134 foreign workers -- among them Victor Lovelady, one of three Americans known to have been killed.

Family members said Lovelady, ever the family man, was excited about the job. He got 28 days off for every 28 days he put in, time he could spend with his wife and two children in Nederland, Texas.

Yes, it was in a remote natural gas facility in Algeria, but Lovelady assured his family it was safe. And it was in Africa, a place the 57-year-old seemed to love.

"He felt something there," his daughter, Erin, told reporters Tuesday. "He was so excited to go there. I don't really know why, but he just loved it."

But 10 days after he returned to the complex from a visit home, terrorists sped in on pickups, overtook the compound and made hostages of its workers.

"It's just unfair," Lovelady's brother, Mike Lovelady, said Tuesday. "My brother didn't deserve to die."

In addition to Lovelady, Americans Gordon Lee Rowan and Frederick Buttaccio also died. Seven U.S. citizens survived the crisis, the State Department said. It did not elaborate, citing privacy concerns.

Like Lovelady, Rowan, too, felt safe working there.

He said "we're in a compound in the middle of nowhere, and we've got security, and I'll be fine," Rowan's former neighbor, Gwen Eckholm, told CNN affiliate KNXV-TV in Phoenix. "I guess you can't really be secure any place."

Meanwhile, Algerian authorities hailed as a hero the only one of their compatriots among the hostages who died in the attack. While few details about his contribution were available Tuesday, Algerian authorities said he had raised the alarm that allowed plant workers to shut down operations and go into hiding.

Militants shot the man between the eyes just as he alerted plant workers of the attack, Algerian Prime Minister Abdelmalek Sellal said.

Al Qaeda in the Islamic Maghreb, the North African branch of the terrorist movement, has claimed responsibility for the attack. In Washington, State Department spokeswoman Victoria Nuland said that U.S. officials "don't have any reason to doubt" the group's involvement.

Nuland said Washington has no reason to believe any Americans are among those still unaccounted for.

Algeria said the attack was retaliation for its decision to let France to use its airspace for an offensive against Islamist militants in neighboring Mali. But regional analysts said that would appear to be unlikely; the operation was too sophisticated to have been planned in the few days between France's intervention in Mali and the attack on the gas plant less than a week later.