1:38 PM PT -- TMZ Sports has obtained Reid's mug shot, which the 35-year-old took after surrendering to authorities Monday.
11:15 AM PT -- Tom Porto, the attorney representing Ariel and her family, said in a statement to TMZ Sports, "[The charge is] absolutely appropriate given the circumstances. Ariel will endure this every day for the rest of her life."
11:06 AM PT -- In court documents obtained by TMZ Sports, officials say Britt's blood alcohol content in the moments after the crash was .113, well above the .08 legal limit.
In the docs, officials also say Britt suffered trauma to his groin in the crash that required emergency surgery.
Officials added they retrieved data from Britt's pickup truck that showed he was going 82.6 MPH in a 65 MPH zone just seconds before the crash, and had reached 83.9 MPH at the time of impact.
The Chiefs released a statement shortly after the charge was filed, saying, "The Kansas City Chiefs organization remains steadfast in our concern for all who have been impacted by this tragic incident."
The team continued, "Our prayers are focused on Ariel's continued healing and recovery. The Chiefs are regularly in contact with the family's designated representative during this challenging time."
Britt Reid -- Andy Reid's son and a former assistant on the Chiefs' coaching staff -- has been hit with a felony DWI charge stemming from his role in a violent Feb. car crash ... law enforcement announced Monday.
In court docs, prosecutors said they've officially levied a "Dwi - Serious Physical Injury" charge on the 35-year-old. If convicted, Britt faces up to 7 years behind bars.
As we previously reported, Britt was involved in a bad 3-car crash near Arrowhead Stadium in Kansas City back on Feb. 4 -- just 3 days before K.C.'s appearance in Super Bowl LV.
Britt was accused of slamming his pickup truck into two cars that had pulled over on the side of the I-435 highway at around 9 p.m.
The collision caused serious injuries to a 5-year-old girl, Ariel Young, who was in a coma following the crash.
According to the girl's family, Ariel remains in the hospital and has been showing signs of improvement ... but "she still has a long road to recovery."
Investigators say Britt had told them he had taken Adderall and drank before getting behind the wheel. They added in court docs Britt did not perform well during field sobriety tests.
Britt had been placed on leave by the Chiefs following the accident ... but he's now no longer employed by the NFL team.
Originally Published -- 11:00 AM PT