"That's concerning for us, given the number one killer on Waikato roads so far this year has been a loss of concentration by drivers resulting in crossing over of the centre line."
Earlier in the day, a man driving a ute towing a trailer and carrying a motorbike collided with a woman driving a Hyundai car on an isolated part of State Highway 4, 50km south of Te Kuiti.
Firefighters had to cut both drivers from their vehicles.
The pair were admitted to Waikato Hospital with serious to critical injuries.
Two dogs riding on the back of the ute were also injured, and were treated by a veterinarian.
Mr Tooman said SH4 was closed for several hours and reopened around 3pm.
Police also attended several other incidents, including a 35-tonne truck tipping over near Taupiri, a car which hit a pedestrian in Hamilton, causing minor injuries, and a man fleeing the scene after crashing his vehicle into another car.
Tuesday night's fatal crash brings this year's road toll in the Waikato police district to 27, compared to 24 over the same period last year.
The Waikato toll is more than double the next highest number of fatalities - 13 in the central North Island police district.
24 HOURS IN WAIKATO
6am Tuesday to 6am yesterday:
1 9.50am SH4/Takiri Rd. Ute-trailer vs car - one man, one woman and two dogs seriously injured.
2 12.36pm Willoughby St, Hamilton. Car vs car - no injuries but one man flees scene.
3 1.15pm Kainui Rd, Taupiri. truck overturns - no injuries.
4 2.14pm Killarney Rd, Hamilton. Car vs car - no injuries.
5 4.49pm Tramway Rd, Hamilton. Car vs car - no injuries.
6 5.41pm Urlich Ave, Hamilton. Car vs car - no injuries.
7 6.08pm Tramway Rd, Hamilton. Car vs car - one woman suffers minor injury.
8 6.55pm Peachgrove Rd, Hamilton. Car vs pedestrian - minor injury to pedestrian.
9 7.08pm Waikato Expressway. Car vs fence - no injuries.
10 9.25pm Kawhia. Car vs car - one man with moderate injuries.
11 11.05pm SH1 Cambridge. Ute vs truck and trailer unit - One man dead, another with minor injury.