Texas Code of Criminal Procedure - CRIM P Art. § 19A.053. Additional Qualified Persons Summoned

(a) If fewer than 16 persons summoned to serve as grand jurors are found to be in attendance and qualified to serve, the court shall order the sheriff or clerk of the district court to summon an additional number of persons considered necessary to constitute a grand jury of 12 grand jurors and four alternate grand jurors.

(b) The sheriff or clerk of the district court shall summon the additional prospective grand jurors under Subsection (a) in person to attend before the court immediately.