(CBS) Kuwaiti authorities said Wednesday they were closing in on the gunman who opened fire on two American civilians stopped at a traffic light, killing one and wounding another. The injured man remained in intensive care Wednesday.

"We have important leads," an Interior Ministry official told The Associated Press, saying an arrest announcement could come later Wednesday.

The official, who spoke on condition of anonymity, refused to elaborate or say whether a prime suspect was in custody or had been identified.

A gunman hiding behind shrubbery about 3 miles from a U.S. military base opened fire Tuesday with a Kalashnikov assault rifle on a sports utility vehicle carrying the two Americans, killing Michael Rene Pouliot, 46, of San Diego, California.

Pouliot was a civilian contractor with Tapestry Solutions software development company working for the U.S. military.

"Everyone is saddened by this tragedy," company spokesman Chris Wahl in San Diego told CBS News.

Tapestry identified the injured man as another employee, David Caraway, a senior software engineer. An al-Razi hospital employee said he was in stable condition and talking on Wednesday. He suffered chest, arm and thigh injuries. Three bullets had been removed, the employee said on condition of anonymity.

Pouliot and Caraway were traveling in a four-wheel-drive Toyota when they came under a hail of bullets from behind trees and bushes near an intersection not far from Camp Doha, the main U.S. military installation in Kuwait where 17,000 U.S. military personnel are stationed.

U.S. Ambassador to Kuwait Richard Jones condemned the incident as a terror attack. Kuwaiti officials denounced the shooting and said it would not affect ties between the two countries.

This was only the latest attack on Americans in Kuwait in the last three months, reports CBS News Correspondent Byron Pitts.

On October 8, a U.S. marine was shot and killed and another wounded by Muslim extremist. On November 21, two U.S. servicemen were shot and wounded by a Kuwaiti policeman. And on Jan. 17, local investigators arrested a Kuwaiti National Guardsman as an alleged Iraqi spy, plotting to poison the food supply of U.S. troops based in Kuwait.

That frightens the 8,000 American civilians working and living in Kuwait.

"The people today weren't in military uniforms," said American Laurence Peters. "They were standing by doing their normal job and they were gunned down."

Small, oil-rich Kuwait was freed in 1991 from a seven-month Iraqi occupation by a U.S-led coalition, and depends on Washington for protection. As U.S. forces pour into the emirate, it could become a launch pad for any war on Iraq.

Tuesday's shooting was the third against American citizens in recent months. On Oct. 8, two Kuwaiti Muslim fundamentalists opened fire on Marines taking a break from war games on the island of Failaka, killing one and injuring another. Other Marines killed the assailants, who reportedly had links to Osama bin Laden's al Qaeda network. A policeman also shot at two U.S. soldiers in their civilian car on a highway on Nov. 21. He was believed to be mentally unstable.

Kuwaiti officials have described the attacks as isolated incidents, distancing themselves from any deeper al Qaeda presence. Fouad al-Hashem, a columnist for the Al-Watan newspaper, wrote Wednesday that the latest shooting had to have been carried out by "Iraqi intelligence agents," or Kuwaitis brainwashed by bin Laden.

Scores of Kuwaitis have fought with Muslim extremists in Afghanistan, Chechnya and Bosnia.

No one has claimed responsibility for Tuesday's attack.