Short answer. Yes. Article 978 puts the descending direct line first, so his children inherit ahead of his parents and his brothers and sisters. The ascending line is reached only when there is nobody in the descending line, and collateral relatives only when both direct lines are empty.
What the law says
Succession pertains, in the first place, to the descending direct line.
Civil Code, Article 978 — Descendants Come First. Read the full provision →
Nine words that fix the order
The rule is as short as it is decisive: succession pertains, in the first place, to the descending direct line. When a person dies without a will, the law does not look around the family for whoever is closest or most deserving; it works through fixed lines in a fixed order, and the descending line — children, and through them grandchildren — comes first. Only if that line is empty does the estate move up to the ascending line of parents and grandparents, and only if that too is empty does it move sideways to brothers, sisters and more distant collateral relatives.
Excluded, not merely postponed
This is the point families most often get wrong. Where children survive, the deceased's parents and siblings do not take a smaller share — they take nothing at all. The line that has priority absorbs the whole estate, so there is no residue for the ones below to divide. It makes no difference how close the deceased was to a brother, how much a parent contributed to the property, or that a sibling nursed him through his last illness. Intestate succession is a default distribution written by statute, and moral claims of that kind have to be provided for in a will if they are to count.
The surviving spouse is the exception to remember
The lines described here are lines of blood relationship, and a widow or widower is in none of them. That does not mean the spouse is shut out. A surviving spouse is a compulsory heir who inherits together with the children rather than waiting behind them, so the practical answer to "who inherits" in most estates is the children and the spouse, concurrently. Beyond that, remember that the surviving spouse's share of the property acquired during the marriage is not inheritance at all — it belongs to her already, and it comes out before the estate to be divided is even measured.
The descending line does not end with children
A common assumption is that if a child has already died, that branch of the family drops out and the parents or siblings move up. It does not work that way. The descending direct line runs through grandchildren and further descendants, who take their deceased parent's place by right of representation, so the line is exhausted only when there is nobody left in it at all. Before concluding that an estate passes to ascendants or collaterals, map the whole descending line, including children of children who predeceased, and confirm each death and each relationship with the civil registry records.