WASHINGTON (AP) — A team of FBI agents was ordered to fly to India to investigate the militants who killed four Americans and injured at least two others during a wave of assaults that ripped through a commercial center of Mumbai.

American officials were working out the final details Friday with Indian diplomats for the departure of the FBI team, U.S. authorities said, speaking on the condition of anonymity because of the sensitivity of the operation. A second group of investigators was on alert to join them if necessary, the officials said.

The investigators aim to learn more about the origins of the militants who carried out the lethal strikes on luxury hotels, a train station and an Orthodox Jewish center where a New York rabbi and his wife were among five hostages slain. An American and his teenage daughter traveling with a Virginia-based spiritual group were also among the 150 people killed during the coordinated attacks.

American lives remained in peril in Mumbai on Friday, the State Department said.

Warning that “Americans are still at risk on the ground,” Gordon Duguid, a State Department spokesman, confirmed the deaths of two Americans in Mumbai, but would not comment further on the victims.

U.S. officials were checking with Indian authorities and hospitals to learn more about the extent of casualties.

The State Department urged Americans not to travel to the stricken city, at least through the weekend.

In New York, the Chabad-Lubavitch movement confirmed Friday that an American Jewish couple was killed during the terrorist assault on the ultra-Conservative group’s Mumbai headquarters.

A Chabad-Lubavitch spokesman, Rabbi Zalman Schmotkin, identified the slain couple as Rabbi Gavriel Noach Holtzberg and his wife, Rivka. The couple, who had dual U.S. and Israeli citizenship, ran the movement’s Mumbai headquarters, which was one of 10 sites attacked. The couple’s toddler son, Moshe Holtzberg, survived the assault and was taken out of the center by an employee, and is now with his grandparents.

A spokeswoman for a meditation group in Virginia said two Americans traveling with the organization in Mumbai were killed. A U.S. official who spoke on condition of anonymity verified that account.

Bobbie Garvey, the spokeswoman for the Synchronicity Foundation, based in Faber, Va., identified the two slain members as Alan Scherr, 58, and his 13-year-old daughter, Naomi.

The meditation group said in a statement that four other members of the 25-person group — two Americans and two Canadians — who were staying at the Oberoi Hotel were wounded by gunfire, and were believed in stable condition.

State Department spokesman Robert McInturff said Thursday he could not identify those injured in Mumbai, but The Associated Press learned the name of one victim: Andi Varagona of Nashville, Tenn. She called her mother from a hospital Thursday and said she had been shot in the arm and leg while eating dinner at the Taj Mahal Palace and Tower hotel.

She said another Tennessee woman traveling with her was also injured, according to the mother, Celeste Varagona, but the woman’s identity was not immediately available.

McInturff said U.S. officials have activated a phone tree to contact American citizens who registered with the U.S. consulate in Mumbai.

A South Asia specialist said Friday that the terror “group itself is probably drawing from, in large numbers, Indian operatives, but it probably enjoys a fairly healthy support of Pakistan.”

“The big picture is that there’s probably going to be more of this, not less of this, to come,” Christine Fair of the RAND Corp. said Friday. “I don’t think this is the most lethal attack that terrorists have perpetrated, but it is certainly the most expansive, in its scope and its scale and its perplexity.”

Pakistan’s ambassador to the U.S., Husain Haqqani, said in a statement that his country is “confronting the menace of terrorism with great vigor.” Haqqani insisted “it is unfair to blame Pakistan or Pakistanis for these acts of terrorism even before an investigation is undertaken.”

A U.S. counterterrorism official also cautioned that it was premature “to reach any hard-and-fast conclusions on who may be responsible for the attacks.” But the official, who spoke on intelligence matters on condition of anonymity, added that “some of what we’re seeing is reminiscent of past terrorist operations undertaken by groups such as Lashkar-e-Taiba and Jaish-e-Mohammed.”

The two groups mentioned by the official are Pakistani militants who have fought Indian troops in Kashmir and are reported to be linked to al-Qaida.

President-elect Barack Obama spoke Thursday by telephone with Secretary of State Condoleezza Rice and received several intelligence briefings. Duguid said that Rice has called Obama twice since the attacks on Mumbai began.

President Bush expressed condolences to Indian Prime Minister Manmohan Singh in a phone call from the Camp David, Md., presidential retreat, where he remained Friday.

The State Department set up a call center for Americans concerned about family members who may be in Mumbai. The number is 1-888-407-4747.