Briefing reporters on Monday, regional governor Krzysztof Komorski said Lublin's crisis management centre received a warning to begin monitoring at 3.09 a.m. local time.
Half an hour later it was told of a "real threat" by Poland's Government Centre for Security (RCB).
A message triggering the siren system reached all seventeen districts simultaneously at 3.44 a.m., but only seven activated their sirens as instructed.
Alarms sounded in the city of Lublin and six neighbouring districts.
Ten others, including Chełm and Zamość, failed to activate their sirens.
Komorski said the process was slowed largely by human hesitation – officials pausing to double-check or consult before pressing the button.
To speed things up, he plans to shift more of that decision-making to a duty officer at the regional crisis centre, who is in direct contact with national security officials, so sirens can eventually be triggered remotely from one place.
Of the region's 364 sirens, only 164 can currently be activated remotely; the rest are analogue.
A tender for 200 additional modern sirens is expected to be settled this week, with a longer-term goal of around 500 sirens region-wide.
Poland's interior minister, Marcin Kierwiński, said separately that a new phone app to improve public warnings would launch within weeks, potentially drawing on the user base of the government's mObywatel app, to complement the existing siren and alert system.
Prosecutors investigating the incident have confirmed the object that crashed near Tarnawa-Kolonia was a Kh-101 missile manufactured in Russia's Moscow region earlier this year, carrying a substantial quantity of explosive material.
Officials said it would have been shot down had it threatened populated areas.
(ał)
Source: PAP