BAGHDAD, Feb. 21 -- A tank truck carrying chlorine exploded in western Baghdad on Wednesday, killing three people and wounding at least 25 in the second such attack in as many days, according to a spokesman for Iraq's Interior Ministry.

Brig. Gen. Sadoun Abdul Karim said that several people exposed to the fumes were taken to hospitals and that the explosion set vehicles and shops on fire.

The chlorine attacks appear to be among deadly tactics adopted by insurgents in recent weeks as the U.S. military and the Iraqi government launch a security plan that will include the deployment of thousands of soldiers to outposts in Baghdad. Insurgents have also displayed new prowess in shooting down U.S. helicopters.

The attack came on a day when the political scandal over the reported rape of a Sunni woman by Iraqi police officers escalated, with the Iraqi prime minister's office releasing what it said was a portion of the woman's medical record.

The medical file, e-mailed to reporters by Prime Minister Nouri al-Maliki's office, includes a highlighted handwritten note with the notation "no vaginal lacerations or obvious injury."

In a simple diagram of the front of the patient's body, there are numerous marks indicating bruises around her inner thighs and groin. There is also a mark indicating a bruise on her head. The woman said she hit her head against the wall as three uniformed police officers raped her Sunday.

The medical record was attached to a news release that said the woman was going to be sued for making up the story.

Maliki said Monday that the rape allegation would be thoroughly investigated by a committee. Hours later, however, he said the investigation concluded that the woman had fabricated the story, and he announced that the accused police officers would be honored.

Maliki, who leads a government dominated by Shiites, did not identify the officers or say why the accolades were justified.

It is unclear how Maliki's office obtained the medical record, but the disclosure of its contents was apparently intended to bolster the conclusion that her story was made up -- and thus defuse a particularly sensitive example of the country's sectarian strife.

The woman has been championed by Sunni politicians, and at least one insurgent group has vowed to carry out attacks against Iraqi security forces in her name. Arab news stations have repeatedly aired a tearful interview in which the woman describes the alleged sexual assault in graphic terms -- a highly unusual move in a country where sex is seldom discussed publicly.

A U.S. military spokesman said Wednesday that he could not immediately confirm the accuracy of the information in the woman's medical record. Military officials have acknowledged that the woman was treated Sunday at the U.S. military-run Ibn Sina Hospital in Baghdad's fortified Green Zone. But they have not disclosed what kind of treatment she received or whether specific tests for rape were administered.

"I don't know how they got it," Capt. John Fleming said about the medical record. "Our policy is we do not release that stuff."

Another U.S. military spokesman, Maj. Gen. William B. Caldwell, said during a news conference Wednesday that the woman was discharged Monday and was provided with a copy of her medical record.

Maliki also announced Wednesday the dismissal of Sunni official Ahmed Abdul Ghafour al-Samaraie, who ran the Sunni Endowment, a government agency that oversees Sunni mosques. Samaraie had called for an international investigation of the woman's allegations, and he said many women have been raped by the country's security forces, which are predominantly Shiite.

Violence continued in Baghdad and elsewhere in Iraq on Wednesday. Bombs exploded in Baghdad, Najaf and Kirkuk, killing at least 15 people, according to police in those regions.

A Black Hawk helicopter was shot down north of Baghdad by rocket-propelled grenades and small arms fire, according to the military. The military said in a statement that none of the nine soldiers aboard suffered serious injuries.

Also on Wednesday, the military disclosed the death of an American soldier killed in northern Baghdad on Tuesday. In addition, the military disclosed the death of a Marine killed Tuesday in Anbar province, in western Iraq. The names were not released.

Caldwell said the first week of the security plan brought a "significant" decrease in sectarian killings, but he noted that the body count remains high because of car bombs and suicide bombers. "The thing we have not been able to bring under control is the number of vehicle-borne IEDs, and in the last few days, the suicide vests," he said, referring to improvised explosive devices. "We think the tactics have slightly switched."

"The effects of the operation will not be seen in days or weeks but over the course of months," he said.

Correspondent Joshua Partlow and special correspondents Saad al-Izzi and Naseer Nouri contributed to this report.