BAGHDAD, Iraq — A rocket attack on the U.S. Embassy yesterday killed two Americans and injured five, the deadliest on the heavily fortified embassy in the 22 months since the U.S. invasion.

The rocket crashed through the ceiling of the embassy's Project and Contracting Office, which disburses reconstruction funds, shortly before 8 p.m. A female civilian and a Navy officer were killed, said Michelle Henry, a spokeswoman for the contracting office.

The rocket attack followed almost two years in which mortar shells fired at the embassy and other targets in the 6-square-mile Green Zone fell largely at random and seldom inflicted major damage or casualties.

Immediately after the rocket attack, debris lay on the floor of the contracting office and the room was filled with a dusty haze, according to an embassy official who reached the scene minutes after the attack. In a sudden quiet that followed the explosion, embassy and military personnel began calling for medics and looking for the injured.

The official, who would not be identified by name because he is not authorized to speak publicly, said he saw an American soldier standing over a woman who lay on the floor. "She looked pretty beaten up," the official said.

"She's dead," the soldier calmly announced.

The fatal strike brought a somber close to what one U.S. military official, speaking as dusk gathered in the tense capital, had termed "a fairly good day." At the time, no U.S. forces had been reported killed; moments later, a roadside bomb in Baghdad killed an American soldier.

In the capital, security around the Green Zone yesterday was extraordinary even by Baghdad standards, giving the city the air of a combat zone. No vehicles were allowed within three blocks of the only public entrance to the fortified complex, protected by tanks at both approaches.

Iraqi police cars, before being allowed to proceed to their precinct house, formed a line to be searched by barrel-chested American security contractors and bomb-sniffing dogs.

Elsewhere in Iraq, insurgent attacks killed at least 16 Iraqis, including nine slain by a suicide bomber in Khanaqin, Iraqi police Capt. Ahmed Nouri said.

In the suicide attack in Khanaqin, a Kurdish-controlled city northeast of Baghdad near the Iranian border, a man blew himself up near a joint Iraqi-American military post with an explosive vest, a device seldom used in Iraq but one that authorities fear could be employed at polling stations.

The insurgent group calling itself Al-Qaida in Iraq claimed responsibility for the Khanaqin attack in an Internet posting.

The were attacks yesterday on polling centers in at least eight cities, from the northern Kurdish city of Dohuk to the southern Shiite stronghold of Basra, although they caused few casualties.

Material from the Chicago Tribune

is included in this report.