In the frosty, early morning fog yesterday, the bodies of two Americans killed by hijackers last week in Iran were solemnly brought home to Andrews Air Force Base, where shivering, mourning family and friends clutched hands and watched military guards unload the caskets.

Vice President Bush was at the air base without a topcoat to greet the plane carrying the bodies of Charles F. Hegna and William L. Stanford, both auditors with the Agency for International Development.

During the brief ceremony, Bush expressed the nation's sympathy to the families and called on all nations to condemn terrorism and see that the hijackers are brought "swiftly and surely to justice."

Hegna's family, including his wife, Edwina Hegna, who live in Sterling, Va., was joined by friends, military officials and about 50 AID employes at the airfield when the C141 cargo plane landed at 7:25 a.m. According to military officials, Stanford's widow, Lorraine Stanford, was at the family's home in Karachi, Pakistan, yesterday.

As an Air Force band played solemnly, two groups of uniformed honor guards dressed in blue coats and white gloves marched up the loading ramp and disappeared into the belly of the plane. Visitors and family then came out of the terminal, led by Bush.

While the honor guards carried the two caskets draped with the American flag, the vice president handed a hankerchief or tissue to Hegna's widow, who stood crying next to him.

Both Hegna, 50, and Stanford, 52, were returning to their posts in Karachi after completing an audit in Yemen when four hijackers commandeered their plane to Tehran. The two men were among 166 people on the Kuwait Airways Airbus that left Kuwait Tuesday, destined for Pakistan. The terrorists had demanded the release of 17 prisoners being held in Kuwait in connection with bombings last year.

After a six-day stand-off, Iranian security officers stormed the plane Sunday and released the remaining seven hostages, including two more Americans, who had been tortured and beaten.

After the national anthem was played at Andrews yesterday and the caskets were put into two white hearses parked nearby, Bush welcomed the visitors who had gathered to witness the return to the "firm soil of America, two of her sons brutally murdered in the service of their country." He extended greetings to the family from President Reagan and said, "We share their pain and outrage."

While the band played "Faith of Our Fathers," the vice president spoke to Edwina Hegna, shook hands with some of the visitors and was ushered off the field while the family and friends quietly dispersed.