Dennis Tuttle, 59, a deceased suspect in Monday's shooting of four Houston Police Department officers and the fatal shooting of two suspects, is seen in this police image from Houston, Texas, U.S., on January 29, 2019. Courtesy HPD/Handout via REUTERS

(Reuters) - Houston authorities are investigating a drug raid on a home last week that left two suspects dead and several officers wounded, amid media reports that an undercover detective was temporarily relieved of duty in connection with the probe.

Officers raided the southeast Houston home of Dennis Tuttle and Rhogena Nicholas on Jan. 28 to serve a narcotics search warrant. Both Tuttle, 59, and Nicholas, 58, were killed in the shootout that followed, according to authorities.

“There is a lot of speculation as to the circumstances regarding this (officer-involved shooting) ... but we urge everyone to let the investigation take its proper course and proceed to conclusion,” Houston Police Chief Art Acevedo said in a statement on Thursday.

Citing the Houston Police Officer’s Union and law enforcement sources, local news channel KHOU11 said the undercover detective was temporarily relieved of duty while investigators probe the “validity of a purported controlled buy of suspected heroin” from the home on Jan. 27 that was reported by officers.

A representative from the union did not immediately respond to requests for comment on Friday. A police department spokesman said he could not confirm the media reports.

The Harris County District Attorney Office’s Civil Rights Division is helping with the investigation, according to the county’s district attorney, Kim Ogg, who said on Thursday that it was standard practice for a shooting involving a police officer.

Acevedo told reporters last week that no heroin was found during the raid, only marijuana and an unidentified white powder believed to be cocaine or prescription painkiller fentanyl, together with three shotguns and two rifles.

A large pit-bull dog that police said tried to attack an officer was also killed during the raid. Five officers were wounded, the police department spokesman said.