Mercado was denied bail and will remain locked up until his arraignment.
The vehicular incident produced numerous injuries to the various members riding in the minivan.
Of the family of six, a toddler was critically injured, as was a 5-year-old passenger who suffered a fractured skull and two broken legs.
Mercado was driving southbound in a 2002 Chevrolet pickup truck when he drifted into the northbound lane, striking the family's 1996 Ford minivan.
The victims' names are being withheld.
